:00:00 2001
From: Eric Wong normalper...@yhbt.net
Date: Fri, 2 Nov 2012 03:47:08 +
Subject: [PATCH] epoll: replace EPOLL_CTL_DISABLE with EPOLL_CTL_POKE
EPOLL_CTL_POKE may be used to force an item into the epoll
ready list. Instead of disabling an item asynchronously
via EPOLL_CTL_DISABLE
Christof Meerwald cme...@cmeerw.org wrote:
On Fri, 2 Nov 2012 04:13:12 +, Eric Wong wrote:
[...]
EPOLL_CTL_POKE may be used to force an item into the epoll
ready list. Instead of disabling an item asynchronously
via EPOLL_CTL_DISABLE, this forces the threads calling
epoll_wait
Hi Neil, I'm wondering if you have or know of any public
documentation/examples for using net_dropmon.
If not, I'll figure it out on my own at some point.
Thanks in advance!
(Not a very high priority project for me, my network connectivity
problems are sadly _very_ obvious at the moment :x)
--
at first, but it does not seem to hurt
performance on my 4-core system. In fact, it was slightly better
(but within margin of error)
time ./eponeshotmt -c 100 -w 4 -t 4 -f 10
real0m 5.78s
user0m 1.20s
sys 0m 21.90s
Tested-by: Eric Wong normalper...@yhbt.net
Hopefully somebody can test
Neil Horman nhor...@tuxdriver.com wrote:
On Fri, Apr 05, 2013 at 07:38:55PM +, Eric Wong wrote:
Hi Neil, I'm wondering if you have or know of any public
documentation/examples for using net_dropmon.
If not, I'll figure it out on my own at some point.
Thanks in advance!
I
).
$ time ./eponeshotmt -c 100 -w 4 -t 4 -f 10
real0m 5.83s
user0m 1.35s
sys 0m 21.95s
I also ran v2 on Davide Libenzi's totalmess epoll stresser for a few
hours yesterday without failures. Running totalmess right now on v3,
so far so good :)
Tested-by: Eric Wong normalper...@yhbt.net
Mathieu Desnoyers mathieu.desnoy...@efficios.com wrote:
It is provided as a starting point only. Test cases should be ported
from Userspace RCU to kernel space and thoroughly ran on a wide range of
architectures before considering this port production-ready.
Hi Mathieu, any progress on this
Oleg Nesterov o...@redhat.com wrote:
On 03/14, Eric Wong wrote:
Oleg Nesterov o...@redhat.com wrote:
On 03/10, Eric Wong wrote:
This fixes the following sparse error when using
CONFIG_SPARSE_RCU_POINTER=y and make C=2 fs/eventpoll.o
fs/eventpoll.c:514:17: error
It is always safe to use RCU_INIT_POINTER to NULL a pointer.
This results in slightly smaller/faster code.
Signed-off-by: Eric Wong normalper...@yhbt.net
Cc: Andrew Morton a...@linux-foundation.org
---
Andrew: Sorry for the noise and requiring these cleanups. Would you
want a squashed commit
In some situations, it is necessary to prepend a node to a queue.
For epoll, this is necessary for two rare conditions:
* when the user triggers -EFAULT
* when reinjecting elements from the ovflist (implemented as a stack)
Signed-off-by: Eric Wong normalper...@yhbt.net
Cc: Mathieu Desnoyers
Pavel Machek pa...@ucw.cz wrote:
Eric Wong wrote:
[1] my splice() annoyances:
* need to create/manage a pipe
* copy size limited by pipe size
* doesn't reduce userspace syscalls (just data copy overhead)
* easy to misuse and starve with blocking sockets + big buffers
cache line and helps improve performance.
* destroy wakeup source immediately for zombie epitems, there is no need
to wait until ep_send_events.
Signed-off-by: Eric Wong normalper...@yhbt.net
Cc: Davide Libenzi davi...@xmailserver.org
Cc: Al Viro v...@zeniv.linux.org.uk
Cc: Andrew Morton a...@linux
Mathieu Desnoyers mathieu.desnoy...@efficios.com wrote:
* Eric Wong (normalper...@yhbt.net) wrote:
In some situations, it is necessary to prepend a node to a queue.
For epoll, this is necessary for two rare conditions:
* when the user triggers -EFAULT
* when reinjecting elements from
Oleg Nesterov o...@redhat.com wrote:
On 03/10, Eric Wong wrote:
This fixes the following sparse error when using
CONFIG_SPARSE_RCU_POINTER=y and make C=2 fs/eventpoll.o
fs/eventpoll.c:514:17: error: incompatible types in comparison expression
(different address spaces
Technically we do not need to hold ep-mtx during ep_free since we are
certain there are no other users of ep at that point. However, lockdep
complains with a suspicious rcu_dereference_check() usage! message;
so lock the mutex before ep_remove to silence the warning.
Signed-off-by: Eric Wong
This reduces the amount of code inside the ready list iteration loops
for better readability IMHO.
Signed-off-by: Eric Wong normalper...@yhbt.net
Cc: Davide Libenzi davi...@xmailserver.org
Cc: Al Viro v...@zeniv.linux.org.uk
Cc: Andrew Morton a...@linux-foundation.org
---
(I think this depends
Mathieu Desnoyers mathieu.desnoy...@efficios.com wrote:
Ported to the Linux kernel from Userspace RCU library, at commit
108a92e5b97ee91b2b902dba2dd2e78aab42f420.
Ref: http://git.lttng.org/userspace-rcu.git
It is provided as a starting point only. Test cases should be ported
from
cleanly to 3.9-rc* since there's no epoll changes in that)
--8---
From 139f0d4528c3fabc6a54e47be73ba9990b42cdd8 Mon Sep 17 00:00:00 2001
From: Eric Wong normalper...@yhbt.net
Date: Thu, 14 Mar 2013 02:37:12 +
Subject: [PATCH] epoll: avoid
Mathieu Desnoyers mathieu.desnoy...@efficios.com wrote:
* Eric Wong (normalper...@yhbt.net) wrote:
Mathieu Desnoyers mathieu.desnoy...@efficios.com wrote:
+/*
+ * Load a data from shared memory.
+ */
+#define CMM_LOAD_SHARED(p) ACCESS_ONCE(p)
When iterating
Mathieu Desnoyers mathieu.desnoy...@efficios.com wrote:
* Eric Wong (normalper...@yhbt.net) wrote:
Mathieu Desnoyers mathieu.desnoy...@efficios.com wrote:
The advantage of using splice() over dequeue() is that you will reduce
the amount of interactions between concurrent enqueue
Eric Wong normalper...@yhbt.net wrote:
Mathieu Desnoyers mathieu.desnoy...@efficios.com wrote:
* Eric Wong (normalper...@yhbt.net) wrote:
Mathieu Desnoyers mathieu.desnoy...@efficios.com wrote:
+/*
+ * Load a data from shared memory.
+ */
+#define CMM_LOAD_SHARED(p
Mathieu Desnoyers mathieu.desnoy...@efficios.com wrote:
Thanks for providing this detailed scenario. I think there is an
important aspect in the use of splice I suggested on which we are not
fully understanding each other. I will annotate your scenario below with
clarifications:
Ah yes, I
Eric Wong normalper...@yhbt.net wrote:
I'm posting this lightly tested version since I may not be able to do
more testing/benchmarking until the weekend.
Still lightly tested (on an initramfs KVM, no real applications, yet).
Davide's totalmess is still running, so that's probably a good sign
Mathieu Desnoyers mathieu.desnoy...@efficios.com wrote:
* Eric Wong (normalper...@yhbt.net) wrote:
Eric Wong normalper...@yhbt.net wrote:
I'm posting this lightly tested version since I may not be able to do
more testing/benchmarking until the weekend.
Still lightly tested
Eric Wong normalper...@yhbt.net wrote:
Mathieu Desnoyers mathieu.desnoy...@efficios.com wrote:
I'm also not entirely sure why you need to add enum epoll_item_state
along with expensive atomic ops to compute the state. Wouldn't it be
enough to know in which queue the nodes are located
The commit epoll: use RCU to protect wakeup_source in epitem
introduced the ep_pm_stay_awake_rcu function for ep_poll_callback
use, but I left it unused on accident. ep-mtx cannot be held in
ep_poll_callback, so RCU should be used here.
Signed-off-by: Eric Wong normalper...@yhbt.net
Cc: Rafael J
-by: Eric Wong normalper...@yhbt.net
Cc: Mathieu Desnoyers mathieu.desnoy...@efficios.com
Cc: Lai Jiangshan la...@cn.fujitsu.com
Cc: Paul E. McKenney paul...@linux.vnet.ibm.com
Cc: Stephen Hemminger shemmin...@vyatta.com
Cc: Davide Libenzi davi...@xmailserver.org
---
Benchmark for this coming
-by: Eric Wong normalper...@yhbt.net
Cc: Davide Libenzi davi...@xmailserver.org
Cc: Al Viro v...@zeniv.linux.org.uk
Cc: Andrew Morton a...@linux-foundation.org
Cc: Mathieu Desnoyers mathieu.desnoy...@efficios.com
---
fs/eventpoll.c | 615 ++---
1
and these new _local
functions is large and outside of the margin of error.
ref: http://www.xmailserver.org/epwbench.c
Somewhat-tested-by: Eric Wong normalper...@yhbt.net
Cc: Mathieu Desnoyers mathieu.desnoy...@efficios.com
Cc: Davide Libenzi davi...@xmailserver.org
Cc: Al Viro v...@zeniv.linux.org.uk
Cc
Eric Wong normalper...@yhbt.net wrote:
This is still not a proper commit, I've lightly tested this.
Btw, full series here (already sent to LKML and some in -mm)
http://yhbt.net/epoll-wfcqueue-v3.8.3-20130321.mbox
(should apply cleanly to all 3.8/3.9 kernels)
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-by: Eric Wong normalper...@yhbt.net
Cc: Mathieu Desnoyers mathieu.desnoy...@efficios.com
Cc: Davide Libenzi davi...@xmailserver.org
Cc: Al Viro v...@zeniv.linux.org.uk
Cc: Andrew Morton a...@linux-foundation.org
---
fs/eventpoll.c | 27 +++
1 file changed, 23 insertions(+), 4
Arve Hjønnevåg a...@android.com wrote:
On Thu, Mar 21, 2013 at 4:52 AM, Eric Wong normalper...@yhbt.net wrote:
Changes since v2:
* epi-state is no longer atomic, we only cmpxchg in ep_poll_callback
now and rely on implicit barriers in other places for reading.
* intermediate
Arve Hjønnevåg a...@android.com wrote:
On Thu, Mar 21, 2013 at 8:24 PM, Eric Wong normalper...@yhbt.net wrote:
With EPOLLET and improper usage (not hitting EAGAIN), the event now
has a larger window to be lost (as mentioned in my changelog).
What about the case where EPOLLET is not set
Mathieu Desnoyers mathieu.desnoy...@efficios.com wrote:
* Eric Wong (normalper...@yhbt.net) wrote:
/*
+ * __wfcq_append_local: append one local queue to another local queue
+ *
+ * No memory barriers are issued. Mutual exclusion is the responsibility
+ * of the caller
Eric Wong normalper...@yhbt.net wrote:
Arve Hjønnevåg a...@android.com wrote:
On Thu, Mar 21, 2013 at 8:24 PM, Eric Wong normalper...@yhbt.net wrote:
With EPOLLET and improper usage (not hitting EAGAIN), the event now
has a larger window to be lost (as mentioned in my changelog
Arve Hjønnevåg a...@android.com wrote:
On Fri, Mar 22, 2013 at 3:31 AM, Eric Wong normalper...@yhbt.net wrote:
Arve Hjønnevåg a...@android.com wrote:
On Thu, Mar 21, 2013 at 8:24 PM, Eric Wong normalper...@yhbt.net wrote:
With EPOLLET and improper usage (not hitting EAGAIN), the event
Eric Wong normalper...@yhbt.net wrote:
Arve Hjønnevåg a...@android.com wrote:
At some point the level triggered event has to get cleared. As far as
I can tell, your new code will drop new events that occur between
revents = ep_item_poll(epi, pt); and epi-state = EP_STATE_IDLE
Sergey Senozhatsky sergey.senozhat...@gmail.com wrote:
[3.163894] ===
[3.163895] [ INFO: suspicious RCU usage. ]
[3.163897] 3.9.0-rc3-next-20130322-dbg-dirty #1 Not tainted
[3.163898] ---
[3.163900] fs/eventpoll.c:545
-off-by: Eric Wong normalper...@yhbt.net
Cc: Mathieu Desnoyers mathieu.desnoy...@efficios.com
Cc: Lai Jiangshan la...@cn.fujitsu.com
Cc: Paul E. McKenney paul...@linux.vnet.ibm.com
Cc: Stephen Hemminger shemmin...@vyatta.com
Cc: Davide Libenzi davi...@xmailserver.org
---
I noticed the original
Mathieu Desnoyers mathieu.desnoy...@efficios.com wrote:
* Eric Wong (normalper...@yhbt.net) wrote:
/*
+ * ___wfcq_append: append one local queue to another local queue
+ *
__wfcq_append() and ___wfcq_append() are meant to be private to
wfcqueue.h. Therefore, the comment above should
Fredrik Tolf fred...@dolda2000.com wrote:
It is worth noting, also, that this seems to be a situation
introduced somewhere between 2.6.26 and 2.6.32, because I started
noticing it when I upgraded from Debian 5.0 to 6.0. I've since tried
it on 3.2.0, 3.5.4 and 3.7.1, and it appears in every
Eric Wong normalper...@yhbt.net wrote:
Hi Arve, looking at commit 4d7e30d98939a0340022ccd49325a3d70f7e0238
(epoll: Add a flag, EPOLLWAKEUP, to prevent suspend ...)
I think the reason for using ep-ws instead of epi-ws in the unlikely
ovflist case applies to the likely rdllist case, too
Putting this on hold for now.
I'm awaiting answers for 20130307112639.ga25...@dcvr.yhbt.net,
(Subject: epoll: possible bug from wakeup_source activation)
this patch may hide the possible bug I'm referring to in that email.
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Arve Hjønnevåg a...@android.com wrote:
On Thu, Mar 7, 2013 at 5:30 PM, Eric Wong normalper...@yhbt.net wrote:
Eric Wong normalper...@yhbt.net wrote:
Hi Arve, looking at commit 4d7e30d98939a0340022ccd49325a3d70f7e0238
(epoll: Add a flag, EPOLLWAKEUP, to prevent suspend ...)
I think
This will prevent us from accidentally introducing a memory bloat
regression here in the future.
Signed-off-by: Eric Wong normalper...@yhbt.net
Cc: Andrew Morton a...@linux-foundation.org
Cc: Davide Libenzi davi...@xmailserver.org,
Cc: Al Viro v...@zeniv.linux.org.uk
---
Andrew Morton
Arve Hjønnevåg a...@android.com wrote:
On Fri, Mar 8, 2013 at 12:49 PM, Eric Wong normalper...@yhbt.net wrote:
What happens if ep_modify calls ep_destroy_wakeup_source
while __pm_stay_awake is running on the same epi-ws?
Yes, that looks like a problem. I think calling
Eric Wong normalper...@yhbt.net wrote:
Arve Hjønnevåg a...@android.com wrote:
On Fri, Mar 8, 2013 at 12:49 PM, Eric Wong normalper...@yhbt.net wrote:
What happens if ep_modify calls ep_destroy_wakeup_source
while __pm_stay_awake is running on the same epi-ws?
Yes, that looks like
: Davide Libenzi davi...@xmailserver.org
Cc: Eric Dumazet eric.duma...@gmail.com
Cc: Oleg Nesterov o...@redhat.com
Signed-off-by: Eric Wong normalper...@yhbt.net
---
Oleg: I found this error since I was working on an unrelated patch
to convert wakeup_source users to RCU in epoll. This was introduced
Eric Dumazet eric.duma...@gmail.com wrote:
On Sun, 2013-03-10 at 01:11 +, Eric Wong wrote:
static void ep_destroy_wakeup_source(struct epitem *epi)
{
- wakeup_source_unregister(epi-ws);
- epi-ws = NULL;
+ struct wakeup_source *ws = epi-ws;
+
+ rcu_assign_pointer
Hi, I'm looking to reduce contention for the ep-lock spin lock in epoll.
I came across wfcqueue in Userspace RCU and am wondering if there's any
reason (other that lack of developer time/users) it hasn't been adapted
for the Linux kernel.
I'd be happy to do the work if it's suitable (and omit
Arve Hjønnevåg a...@android.com wrote:
On Fri, Mar 8, 2013 at 11:10 PM, Eric Wong normalper...@yhbt.net wrote:
Arve Hjønnevåg a...@android.com wrote:
On Fri, Mar 8, 2013 at 12:49 PM, Eric Wong normalper...@yhbt.net wrote:
What happens if ep_modify calls ep_destroy_wakeup_source
while
Arve Hjønnevåg a...@android.com wrote:
On Mon, Mar 11, 2013 at 5:17 PM, Eric Wong normalper...@yhbt.net wrote:
Arve Hjønnevåg a...@android.com wrote:
On Fri, Mar 8, 2013 at 11:10 PM, Eric Wong normalper...@yhbt.net wrote:
Arve Hjønnevåg a...@android.com wrote:
On Fri, Mar 8, 2013 at 12
Eric Wong normalper...@yhbt.net wrote:
Events arriving in ovflist are stored in LIFO order, so
we should account for that when inserting them into rddlist.
Fwiw, I noticed this oddity because I wanted to start tracing epitem
readiness (to detect when my application is not calling epoll_wait
This makes the kernel slightly smaller, and hopefully easier to follow.
Signed-off-by: Eric Wong normalper...@yhbt.net
Cc: Davide Libenzi davi...@xmailserver.org
Cc: Al Viro v...@zeniv.linux.org.uk
Cc: Andrew Morton a...@linux-foundation.org
---
fs/eventpoll.c | 27 +++
1
-off-by: Eric Wong normalper...@yhbt.net
Cc: Davide Libenzi davi...@xmailserver.org
Cc: Al Viro v...@zeniv.linux.org.uk
Cc: Andrew Morton a...@linux-foundation.org
---
fs/eventpoll.c | 35 +++-
include/linux/eventpoll.h| 8 +++
include/trace/events/eventpoll.h
Ulrich Drepper drep...@gmail.com wrote:
On Mon, Feb 25, 2013 at 2:22 PM, Eric Dumazet eric.duma...@gmail.com wrote:
I don't understand the issue.
sendfile() returns -EAGAIN only if no bytes were copied to the socket.
There is something wrong/unexpected/...
I have a program which can
instead of __attribute__((packed))
Signed-off-by: Eric Wong normalper...@yhbt.net
Cc: Davide Libenzi davi...@xmailserver.org
Cc: Al Viro v...@zeniv.linux.org.uk
Cc: Andrew Morton a...@linux-foundation.org
---
fs/eventpoll.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs
@@
struct epoll_filefd {
struct file *file;
int fd;
-} EPOLL_PACKED;
+} __packed;
Thanks for testing on ppc. Looks good to me. For what it's worth:
Acked-by: Eric Wong normalper...@yhbt.net
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the body of a message
Hi Arve, looking at commit 4d7e30d98939a0340022ccd49325a3d70f7e0238
(epoll: Add a flag, EPOLLWAKEUP, to prevent suspend ...)
I think the reason for using ep-ws instead of epi-ws in the unlikely
ovflist case applies to the likely rdllist case, too. Since epi-ws is
only protected by ep-mtx, it can
David Miller da...@davemloft.net wrote:
From: Eric Dumazet eric.duma...@gmail.com
Date: Fri, 18 Jan 2013 22:13:16 -0800
On Fri, 2013-01-18 at 21:54 -0800, Eric Dumazet wrote:
Hmm, this might be already fixed in net-next tree, could you try it ?
Yes, running your program on
Andy Lutomirski l...@amacapital.net wrote:
On Thu, Feb 7, 2013 at 12:11 PM, Martin Sustrik sust...@250bpm.com wrote:
On 07/02/13 20:12, Andy Lutomirski wrote:
On 02/06/2013 10:41 PM, Martin Sustrik wrote:
The value of 'events' should be any combination of event flags as defined
by
Martin Sustrik sust...@250bpm.com wrote:
On 07/02/13 23:44, Andrew Morton wrote:
That's a nice changelog but it omitted a critical thing: why do you
think the kernel needs this feature? What's the value and use case for
being able to poll these descriptors?
To address the question, I've
Martin Sustrik sust...@250bpm.com wrote:
On 08/02/13 23:21, Eric Wong wrote:
Martin Sustriksust...@250bpm.com wrote:
To address the question, I've written down detailed description of
the challenges of the network protocol development in user space and
how the proposed feature addresses
Martin Sustrik sust...@250bpm.com wrote:
On 09/02/13 04:54, Eric Wong wrote:
Using one eventfd per userspace socket still seems a bit wasteful.
Wasteful in what sense? Occupying a slot in file descriptor table?
That's the price for having the socket uniquely identified by the
fd.
Yes. I
Events arriving in ovflist are stored in LIFO order, so
we should account for that when inserting them into rddlist.
Signed-off-by: Eric Wong normalper...@yhbt.net
Cc: Davide Libenzi davi...@xmailserver.org
Cc: Al Viro v...@zeniv.linux.org.uk
Cc: Andrew Morton a...@linux-foundation.org
---
I
With the following flow, I'm sometimes getting an unexpected EOF on the
pipe reader even though I never close the pipe writer:
tcp_wr -write- tcp_rd -splice- pipe_wr - pipe_rd -splice- /dev/null
I encounter this in in 3.7.3, 3.8-rc3, and the latest from Linus
Eric Dumazet eric.duma...@gmail.com wrote:
On Fri, 2013-01-18 at 21:54 -0800, Eric Dumazet wrote:
Hmm, this might be already fixed in net-next tree, could you try it ?
Yes, running your program on net-next seems OK.
David, we need the two following commits.
commit
Jeremy Allison j...@samba.org wrote:
On Thu, Feb 21, 2013 at 01:51:53PM +, Myklebust, Trond wrote:
On Thu, 2013-02-21 at 12:37 +0100, Ric Wheeler wrote:
We have debated the need to have a system call to allow for offloading
copy
operations, for example to an NFS server (part to
Phillip Susi ps...@ubuntu.com wrote:
On Sat, Dec 15, 2012 at 12:54:48AM +, Eric Wong wrote:
strace -T timing on an uncached, one gigabyte file:
Before: fadvise64(3, 0, 0, POSIX_FADV_WILLNEED) = 0 2.484832
After: fadvise64(3, 0, 0, POSIX_FADV_WILLNEED) = 0 0.61
It shouldn't
Myklebust, Trond trond.mykleb...@netapp.com wrote:
-Original Message-
From: Zach Brown [mailto:z...@redhat.com]
Sent: Thursday, February 21, 2013 5:25 PM
To: Myklebust, Trond
Cc: Paolo Bonzini; Ric Wheeler; Linux FS Devel;
linux-kernel@vger.kernel.org;
Chris L. Mason;
Andreas Voellmy andreas.voel...@yale.edu wrote:
There were a couple of errors in the code when I posted my last
message. I have fixed those. The epoll bug still occurs.
Sorry I haven't gotten around to this.
Can you reproduce this with fewer cores? (I only have 4 at most).
Have you tried the
Andreas Voellmy andreas.voel...@yale.edu wrote:
I wrote a C program that behaves similar to my original program and
triggers the bug. The bug only arises when I use enough cores and
threads (about 16). The program is here:
https://github.com/AndreasVoellmy/epollbug/blob/master/epollbug.c
I
Junchang(Jason) Wang junchang.w...@yale.edu wrote:
We still believe this is a bug in epoll system even though we can't
prove that so far. Both Andi and I are very interested in this problem
and helping you experts solve this it. Just let us know if we can
help.
I'm just another epoll user,
...@fromorbit.com
Cc: Zheng Liu gnehzuil@gmail.com
Signed-off-by: Eric Wong normalper...@yhbt.net
---
I have not tested on NUMA (since I've no access to NUMA hardware)
and do not know how the use of the workqueue affects RA performance.
I'm only using WQ_UNBOUND on non-NUMA, though.
I'm
== pthread_join(rs, NULL));
assert(0 == pthread_join(r, NULL));
return 0;
}
8
Any help/suggestions/test patches would be greatly appreciated.
Thanks for reading!
--
Eric Wong
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Eric Wong normalper...@yhbt.net wrote:
I'm finding ppoll() unexpectedly stuck when waiting for POLLIN on a
local TCP socket. The isolated code below can reproduces the issue
after many minutes (1 hour). It might be easier to reproduce on
a busy system while disk I/O is happening.
Ugh, I
Eric Wong normalper...@yhbt.net wrote:
Eric Wong normalper...@yhbt.net wrote:
I'm finding ppoll() unexpectedly stuck when waiting for POLLIN on a
local TCP socket. The isolated code below can reproduces the issue
after many minutes (1 hour). It might be easier to reproduce on
a busy
() barrier in poll_schedule_timeout() appears to be
insufficient on my SMP x86-64 machine (as it's only an xchg()).
This may also be related to the epoll issue described by
Andreas Voellmy in http://thread.gmane.org/gmane.linux.kernel/1408782/
Signed-off-by: Eric Wong normalper...@yhbt.net
Cc: Hans
Eric Wong normalper...@yhbt.net wrote:
This patch seems to fix my issue with ppoll() being stuck on my
SMP machine: http://article.gmane.org/gmane.linux.file-systems/70414
OK, it doesn't fix my issue, but it seems to make it harder-to-hit...
The change to sock_poll_wait() in
commit
Eric Dumazet eric.duma...@gmail.com wrote:
On Mon, 2012-12-31 at 13:21 +, Eric Wong wrote:
This patch seems to fix my issue with ppoll() being stuck on my
SMP machine: http://article.gmane.org/gmane.linux.file-systems/70414
The change to sock_poll_wait() in
commit
Eric Wong normalper...@yhbt.net wrote:
Eric Dumazet eric.duma...@gmail.com wrote:
commit 626cf236608505d376e4799adb4f7eb00a8594af should not have this
side effect, at least for poll()/select() functions. The epoll() changes
I am not yet very confident.
I have a better explanation
it.
--- 8
From 02f43757d04bb6f2786e79eecf1cfa82e6574379 Mon Sep 17 00:00:00 2001
From: Eric Wong normalper...@yhbt.net
Date: Tue, 1 Jan 2013 21:20:27 +
Subject: [PATCH] epoll: prevent missed events on EPOLL_CTL_MOD
EPOLL_CTL_MOD sets the interest mask before
Eric Dumazet eric.duma...@gmail.com wrote:
First, thanks for working on this issue.
No problem!
It seems the real problem is the epi-event.events = event-events;
which is done without taking ep-lock
Yes. I am hoping it is possible to do it without a lock there,
but your change is more
Eric Dumazet eric.duma...@gmail.com wrote:
On Wed, 2013-01-02 at 18:40 +, Eric Wong wrote:
Eric Dumazet eric.duma...@gmail.com wrote:
It seems the real problem is the epi-event.events = event-events;
which is done without taking ep-lock
Yes. I am hoping it is possible to do
(changing Cc:)
Eric Wong normalper...@yhbt.net wrote:
I'm finding ppoll() unexpectedly stuck when waiting for POLLIN on a
local TCP socket. The isolated code below can reproduces the issue
after many minutes (1 hour). It might be easier to reproduce on
a busy system while disk I/O
Eric Wong normalper...@yhbt.net wrote:
[1] my full setup is very strange.
Other than the FUSE component I forgot to mention, little depends on
the kernel. With all this, the standalone toosleepy can get stuck.
I'll try to reproduce it with less...
I just confirmed my toosleepy
Eric Wong normalper...@yhbt.net wrote:
Linus Torvalds torva...@linux-foundation.org wrote:
Please document the barrier that this mb() pairs with, and then give
an explanation for the fix in the commit message, and I'll happily
take it. Even if it's just duplicating the comments above
Eric Dumazet eric.duma...@gmail.com wrote:
On Wed, 2013-01-02 at 20:47 +, Eric Wong wrote:
Eric Wong normalper...@yhbt.net wrote:
[1] my full setup is very strange.
Other than the FUSE component I forgot to mention, little depends on
the kernel. With all
Eric Wong normalper...@yhbt.net wrote:
Eric Dumazet eric.duma...@gmail.com wrote:
With the following patch, I cant reproduce the 'apparent stuck'
Right, the output is just an approximation and the logic there
was bogus.
Thanks for looking at this.
I'm still able to reproduce the issue
Eric Wong normalper...@yhbt.net wrote:
I think this requires frequent dirtying/cycling of pages to reproduce.
(from copying large files around) to interact with compaction.
I'll see if I can reproduce the issue with read-only FS activity.
Still successfully running the read-only test on my
Eric Wong normalper...@yhbt.net wrote:
Eric Wong normalper...@yhbt.net wrote:
I think this requires frequent dirtying/cycling of pages to reproduce.
(from copying large files around) to interact with compaction.
I'll see if I can reproduce the issue with read-only FS activity.
Still
Mel Gorman mgor...@suse.de wrote:
On Wed, Jan 02, 2013 at 08:08:48PM +, Eric Wong wrote:
Instead, I disabled THP+compaction under v3.7.1 and I've been unable to
reproduce the issue without THP+compaction.
Implying that it's stuck in compaction somewhere. It could be the case
Mel Gorman mgor...@suse.de wrote:
On Wed, Jan 02, 2013 at 08:08:48PM +, Eric Wong wrote:
Instead, I disabled THP+compaction under v3.7.1 and I've been unable to
reproduce the issue without THP+compaction.
Implying that it's stuck in compaction somewhere. It could be the case
Andreas Voellmy andreas.voel...@yale.edu wrote:
Using strace, I checked that my program is using epoll api as I
described. Here is a fragment of the strace output that demonstrates
my use:
recvfrom(161, GET / HTTP/1.1\r\nHost: 10.12.0.1:..., 90, 0, NULL, NULL) = 90
sendto(161, HTTP/1.1 200
should not hurt existing applications.
strace -T timing on an uncached, one gigabyte file:
Before: fadvise64(3, 0, 0, POSIX_FADV_WILLNEED) = 0 2.484832
After: fadvise64(3, 0, 0, POSIX_FADV_WILLNEED) = 0 0.61
Signed-off-by: Eric Wong normalper...@yhbt.net
---
N.B.: I'm not sure if I'm
Alan Cox a...@lxorguk.ukuu.org.uk wrote:
On Sat, 15 Dec 2012 00:54:48 +
Eric Wong normalper...@yhbt.net wrote:
Applications streaming large files may want to reduce disk spinups and
I/O latency by performing large amounts of readahead up front
How does it compare benchmark wise
xtu4 xiaobing...@intel.com wrote:
resend it, due to format error
Subject: [PATCH] when system in low memory scenario, imaging there is a mp3
play, ora video play, we need to read mp3 or video file
from memory to page cache,but when system lack of memory,
page cache of mp3 or video file
Dave Chinner da...@fromorbit.com wrote:
On Sat, Dec 15, 2012 at 12:54:48AM +, Eric Wong wrote:
Applications streaming large files may want to reduce disk spinups and
I/O latency by performing large amounts of readahead up front.
Applications also tend to read files soon after opening
Eric Wong normalper...@yhbt.net wrote:
Perhaps squashing something like the following will work?
Last hunk should've had a return before skip_ra:
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -264,6 +266,10 @@ void wq_page_cache_readahead(struct address_space
*mapping, struct file *filp
Dave Chinner da...@fromorbit.com wrote:
On Sun, Dec 16, 2012 at 12:25:49AM +, Eric Wong wrote:
Alan Cox a...@lxorguk.ukuu.org.uk wrote:
On Sat, 15 Dec 2012 00:54:48 +
Eric Wong normalper...@yhbt.net wrote:
Applications streaming large files may want to reduce disk spinups
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