On 01/19/2016 07:08 PM, tip-bot for Raghavendra K T wrote:
Commit-ID: 9c03ee147193645be4c186d3688232fa438c57c7
Gitweb: http://git.kernel.org/tip/9c03ee147193645be4c186d3688232fa438c57c7
Author: Raghavendra K T
AuthorDate: Sat, 16 Jan 2016 00:31:23 +0530
Committer: Ingo Molnar
use local_memory_node(), which is guaranteed to have memory.
local_memory_node is a noop in other architectures that does not support
memoryless nodes.
Signed-off-by: Raghavendra K T
---
block/blk-mq-cpumap.c | 2 +-
block/blk-mq.c| 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
Validated
hctx->cpumask is already populated and let the tag cpumask follow that
instead of going through a new for loop.
Signed-off-by: Raghavendra K T
---
block/blk-mq.c | 9 +
1 file changed, 1 insertion(+), 8 deletions(-)
Nish had suggested to put cpumask_copy after WARN_ON (instead
On 11/24/2015 02:43 AM, Tejun Heo wrote:
Hello,
On Thu, Nov 19, 2015 at 03:54:35PM +0530, Raghavendra K T wrote:
While I was creating thousands of docker container on a power8 baremetal
(config: 4.3.0 kernel 1TB RAM, 20core (=160 cpu) system. After creating
around 5600 container
I have hit
On 11/24/2015 02:43 AM, Tejun Heo wrote:
Hello,
On Thu, Nov 19, 2015 at 03:54:35PM +0530, Raghavendra K T wrote:
While I was creating thousands of docker container on a power8 baremetal
(config: 4.3.0 kernel 1TB RAM, 20core (=160 cpu) system. After creating
around 5600 container
I have hit
Hi,
While I was creating thousands of docker container on a power8 baremetal
(config: 4.3.0 kernel 1TB RAM, 20core (=160 cpu) system. After creating
around 5600 container
I have hit below problem.
[This is looking similar to
https://bugzilla.kernel.org/show_bug.cgi?id=101011, but
kernel had Re
On 10/13/2015 10:17 PM, Jeff Moyer wrote:
Raghavendra K T writes:
In nr_hw_queues >1 cases when certain number of cpus are onlined/or
offlined, that results change in request_queue map in block-mq layer,
we see the kernel dumping like:
What version is that patch against? This prob
new mapping does not cause problem.
That is also fixed with this change.
This problem is originally found in powervm which had 160 cpus (SMT8),
128 nr_hw_queues. The dump was easily reproduced with offlining last core
and it has been a blocker issue because cpu hotplug is a common case for
DLPAR.
On 10/06/2015 03:55 PM, Michael Ellerman wrote:
On Sun, 2015-09-27 at 23:59 +0530, Raghavendra K T wrote:
Problem description:
Powerpc has sparse node numbering, i.e. on a 4 node system nodes are
numbered (possibly) as 0,1,16,17. At a lower level, we map the chipid
got from device tree is
On 10/06/2015 03:47 PM, Michael Ellerman wrote:
On Sun, 2015-27-09 at 18:29:09 UTC, Raghavendra K T wrote:
We access numa_cpu_lookup_table array directly in all the places
to read/update numa cpu lookup information. Instead use a helper
function to update.
This is helpful in changing the way
On 09/30/2015 01:16 AM, Denis Kirjanov wrote:
On 9/29/15, Raghavendra K T wrote:
On 09/28/2015 10:34 PM, Nishanth Aravamudan wrote:
On 28.09.2015 [13:44:42 +0300], Denis Kirjanov wrote:
On 9/27/15, Raghavendra K T wrote:
Problem description:
Powerpc has sparse node numbering, i.e. on a 4
On 09/28/2015 11:05 PM, Nishanth Aravamudan wrote:
On 27.09.2015 [23:59:11 +0530], Raghavendra K T wrote:
Once we have made the distinction between nid and chipid
create a 1:1 mapping between them. This makes compacting the
nids easy later.
No functionality change.
Signed-off-by: Raghavendra
On 09/28/2015 11:04 PM, Nishanth Aravamudan wrote:
On 27.09.2015 [23:59:08 +0530], Raghavendra K T wrote:
[...]
2) Map the sparse chipid got from device tree to a serial nid at kernel
level (The idea proposed in this series).
Pro: It is more natural to handle at kernel level than at lower
On 09/28/2015 11:02 PM, Nishanth Aravamudan wrote:
On 27.09.2015 [23:59:12 +0530], Raghavendra K T wrote:
Create arrays that maps serial nids and sparse chipids.
Note: My original idea had only two arrays of chipid to nid map. Final
code is inspired by driver/acpi/numa.c that maps a proximity
On 09/28/2015 10:58 PM, Nishanth Aravamudan wrote:
On 27.09.2015 [23:59:11 +0530], Raghavendra K T wrote:
Once we have made the distinction between nid and chipid
create a 1:1 mapping between them. This makes compacting the
nids easy later.
Didn't the previous patch just do the opposi
On 09/28/2015 10:57 PM, Nishanth Aravamudan wrote:
On 27.09.2015 [23:59:10 +0530], Raghavendra K T wrote:
There is no change in the fuctionality
Signed-off-by: Raghavendra K T
---
arch/powerpc/mm/numa.c | 42 +-
1 file changed, 21 insertions(+), 21
On 09/28/2015 10:34 PM, Nishanth Aravamudan wrote:
On 28.09.2015 [13:44:42 +0300], Denis Kirjanov wrote:
On 9/27/15, Raghavendra K T wrote:
Problem description:
Powerpc has sparse node numbering, i.e. on a 4 node system nodes are
numbered (possibly) as 0,1,16,17. At a lower level, we map the
On 09/27/2015 11:59 PM, Raghavendra K T wrote:
We access numa_cpu_lookup_table array directly in all the places
to read/update numa cpu lookup information. Instead use a helper
function to update.
This is helpful in changing the way numa<-->cpu mapping in single
place when needed.
Thi
Once we have made the distinction between nid and chipid
create a 1:1 mapping between them. This makes compacting the
nids easy later.
No functionality change.
Signed-off-by: Raghavendra K T
---
arch/powerpc/mm/numa.c | 36 +---
1 file changed, 29 insertions
: cleanup patches
patch 4: Adds helper function to map nid and chipid
patch 5: Uses the mapping to get serial nid
Raghavendra K T (5):
powerpc:numa Add numa_cpu_lookup function to update lookup table
powerpc:numa Rename functions referring to nid as chipid
powerpc:numa create 1:1 mappaing
and cpus
2) Running the tests from numactl source.
3) Creating 1000s of docker containers stressing the system
Signed-off-by: Raghavendra K T
---
arch/powerpc/mm/numa.c | 13 -
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm
nality.
Signed-off-by: Raghavendra K T
---
arch/powerpc/include/asm/mmzone.h | 2 +-
arch/powerpc/kernel/smp.c | 10 +-
arch/powerpc/mm/numa.c| 28 +---
3 files changed, 23 insertions(+), 17 deletions(-)
diff --git a/arch/powerpc/include/asm/mmzon
in first unused
nid easily by knowing first unset bit in the mask.
No change in functionality.
Signed-off-by: Raghavendra K T
---
arch/powerpc/mm/numa.c | 48 +++-
1 file changed, 47 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/mm/numa.c b
There is no change in the fuctionality
Signed-off-by: Raghavendra K T
---
arch/powerpc/mm/numa.c | 42 +-
1 file changed, 21 insertions(+), 21 deletions(-)
diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index d5e6eee..f84ed2f 100644
--- a
* Michael Ellerman [2015-09-22 15:29:03]:
> On Tue, 2015-09-15 at 07:38 +0530, Raghavendra K T wrote:
> >
> > ... nothing
>
> Sure this patch looks obvious, but please give me a changelog that proves
> you've thought about it thoroughly.
>
> For example is i
On 09/22/2015 10:59 AM, Michael Ellerman wrote:
On Tue, 2015-09-15 at 07:38 +0530, Raghavendra K T wrote:
... nothing
Sure this patch looks obvious, but please give me a changelog that proves
you've thought about it thoroughly.
For example is it OK to use for_each_node() at this poi
On 09/15/2015 07:38 AM, Raghavendra K T wrote:
The functions used in the patch are in slowpath, which gets called
whenever alloc_super is called during mounts.
Though this should not make difference for the architectures with
sequential numa node ids, for the powerpc which can potentially have
p (Vldimir)
- Add comment that node 0 should always be present (Vladimir)
Raghavendra K T (2):
mm: Replace nr_node_ids for loop with for_each_node in list lru
powerpc:numa Do not allocate bootmem memory for non existing nodes
arch/powerpc/mm/numa.c | 2 +-
mm/list_lru.c
Signed-off-by: Raghavendra K T
---
arch/powerpc/mm/numa.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index 8b9502a..8d8a541 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -80,7 +80,7 @@ static void
numa ids, 0,1,16,17
is common), this patch saves some unnecessary allocations for
non existing numa nodes.
Even without that saving, perhaps patch makes code more readable.
[ Take memcg_aware check outside for_each loop: Vldimir]
Signed-off-by: Raghavendra K T
---
mm/list_lru.c | 34
On 09/14/2015 05:34 PM, Vladimir Davydov wrote:
On Mon, Sep 14, 2015 at 05:09:31PM +0530, Raghavendra K T wrote:
On 09/14/2015 02:30 PM, Vladimir Davydov wrote:
On Wed, Sep 09, 2015 at 12:01:46AM +0530, Raghavendra K T wrote:
The functions used in the patch are in slowpath, which gets called
On 09/14/2015 02:30 PM, Vladimir Davydov wrote:
Hi,
On Wed, Sep 09, 2015 at 12:01:46AM +0530, Raghavendra K T wrote:
The functions used in the patch are in slowpath, which gets called
whenever alloc_super is called during mounts.
Though this should not make difference for the architectures
numa ids, 0,1,16,17
is common), this patch saves some unnecessary allocations for
non existing numa nodes.
Even without that saving, perhaps patch makes code more readable.
Signed-off-by: Raghavendra K T
---
mm/list_lru.c | 23 +++
1 file changed, 15 insertions(+), 8 deletions
Signed-off-by: Raghavendra K T
---
arch/powerpc/mm/numa.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index 8b9502a..8d8a541 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -80,7 +80,7 @@ static void
loop with for_each_node so that allocations happen only for
existing numa nodes.
Please note that, though there are many places where nr_node_ids is used,
current patchset uses for_each_node only for slowpath to avoid find_next_bit
traversal.
Raghavendra K T (2):
mm: Replace nr_node_ids for loop with for_ea
Signed-off-by: Raghavendra K T
---
include/net/ip.h | 10 ++
net/ipv4/af_inet.c | 41 +++--
2 files changed, 37 insertions(+), 14 deletions(-)
diff --git a/include/net/ip.h b/include/net/ip.h
index d5fe9f2..93bf12e 100644
--- a/include/net/ip.h
[kernel.kallsyms] [k] veth_stats_one
changes/ideas suggested:
Using buffer in stack (Eric), Usage of memset (David), Using memcpy in
place of unaligned_put (Joe).
Signed-off-by: Raghavendra K T
---
net/ipv6/addrconf.c | 26 --
1 file changed, 16 insertions(+), 10 deletions
cache-misses: 1.41 %
Please let me know if you have suggestions/comments.
Thanks Eric, Joe and David for the comments.
Raghavendra K T (2):
net: Introduce helper functions to get the per cpu data
net: Optimize snmp stat aggregation by walking all the percpu data at
On 08/29/2015 08:51 PM, Joe Perches wrote:
On Sat, 2015-08-29 at 07:32 -0700, Eric Dumazet wrote:
On Sat, 2015-08-29 at 14:37 +0530, Raghavendra K T wrote:
static inline void __snmp6_fill_stats64(u64 *stats, void __percpu *mib,
- int items, int bytes
Signed-off-by: Raghavendra K T
---
include/net/ip.h | 10 ++
net/ipv4/af_inet.c | 41 +++--
2 files changed, 37 insertions(+), 14 deletions(-)
diff --git a/include/net/ip.h b/include/net/ip.h
index d5fe9f2..93bf12e 100644
--- a/include/net/ip.h
[kernel.kallsyms] [k] veth_stats_one
changes/ideas suggested:
Using buffer in stack (Eric), Usage of memset (David), Using memcpy in
place of unaligned_put (Joe).
Signed-off-by: Raghavendra K T
---
net/ipv6/addrconf.c | 22 +-
1 file changed, 13 insertions(+), 9 deletions(-)
Changes
.47% docker docker[.] strings.FieldsFunc
cache-misses: 1.41 %
Please let me know if you have suggestions/comments.
Thanks Eric, Joe and David for comments on V1 and V2.
Raghavendra K T (2):
net: Introduc
On 08/29/2015 10:41 AM, David Miller wrote:
From: Raghavendra K T
Date: Sat, 29 Aug 2015 08:27:15 +0530
resending the patch with memset. Please let me know if you want to
resend all the patches.
Do not post patches as replies to existing discussion threads.
Instead, make a new, fresh
On 08/29/2015 08:56 AM, Eric Dumazet wrote:
On Sat, 2015-08-29 at 08:27 +0530, Raghavendra K T wrote:
/* Use put_unaligned() because stats may not be aligned for u64. */
put_unaligned(items, &stats[0]);
for (i = 1; i < items; i++)
- put_un
* David Miller [2015-08-28 11:24:13]:
> From: Raghavendra K T
> Date: Fri, 28 Aug 2015 12:09:52 +0530
>
> > On 08/28/2015 12:08 AM, David Miller wrote:
> >> From: Raghavendra K T
> >> Date: Wed, 26 Aug 2015 23:07:33 +0530
> >>
> &
On 08/28/2015 12:08 AM, David Miller wrote:
From: Raghavendra K T
Date: Wed, 26 Aug 2015 23:07:33 +0530
@@ -4641,10 +4647,12 @@ static inline void __snmp6_fill_stats64(u64 *stats,
void __percpu *mib,
static void snmp6_fill_stats(u64 *stats, struct inet6_dev *idev, int attrtype
Signed-off-by: Raghavendra K T
---
include/net/ip.h | 10 ++
net/ipv4/af_inet.c | 41 +++--
2 files changed, 37 insertions(+), 14 deletions(-)
diff --git a/include/net/ip.h b/include/net/ip.h
index d5fe9f2..93bf12e 100644
--- a/include/net/ip.h
[kernel.kallsyms] [k] _raw_spin_lock
Signed-off-by: Raghavendra K T
---
net/ipv6/addrconf.c | 18 +-
1 file changed, 13 insertions(+), 5 deletions(-)
Change in V2:
- Allocate stat calculation buffer in stack (Eric)
Thanks David and Eric for coments on V1 and as both of them
lease let me know if you have suggestions/comments.
Thanks Eric and David for comments on V1.
Raghavendra K T (2):
net: Introduce helper functions to get the per cpu data
net: Optimize snmp stat aggregation by walking all the percpu data at
once
include/net/ip.h| 10 +++
On 08/26/2015 07:39 PM, Eric Dumazet wrote:
On Wed, 2015-08-26 at 15:55 +0530, Raghavendra K T wrote:
On 08/26/2015 04:37 AM, David Miller wrote:
From: Raghavendra K T
Date: Tue, 25 Aug 2015 13:24:24 +0530
Please let me know if you have suggestions/comments.
Like Eric Dumazet said the
On 08/25/2015 09:30 PM, Eric Dumazet wrote:
On Tue, 2015-08-25 at 21:17 +0530, Raghavendra K T wrote:
On 08/25/2015 07:58 PM, Eric Dumazet wrote:
This is a great idea, but kcalloc()/kmalloc() can fail and you'll crash
the whole kernel at this point.
Good catch, and my bad. Though s
On 08/26/2015 04:37 AM, David Miller wrote:
From: Raghavendra K T
Date: Tue, 25 Aug 2015 13:24:24 +0530
Please let me know if you have suggestions/comments.
Like Eric Dumazet said the idea is good but needs some adjustments.
You might want to see whether a per-cpu work buffer works for
On 08/25/2015 09:30 PM, Eric Dumazet wrote:
On Tue, 2015-08-25 at 21:17 +0530, Raghavendra K T wrote:
On 08/25/2015 07:58 PM, Eric Dumazet wrote:
This is a great idea, but kcalloc()/kmalloc() can fail and you'll crash
the whole kernel at this point.
Good catch, and my bad. Though s
On 08/25/2015 08:03 PM, Eric Dumazet wrote:
On Tue, 2015-08-25 at 13:24 +0530, Raghavendra K T wrote:
While creating 1000 containers, perf is showing lot of time spent in
snmp_fold_field on a large cpu system.
The current patch tries to improve by reordering the statistics gathering.
Please
On 08/25/2015 07:58 PM, Eric Dumazet wrote:
On Tue, 2015-08-25 at 13:24 +0530, Raghavendra K T wrote:
Docker container creation linearly increased from around 1.6 sec to 7.5 sec
(at 1000 containers) and perf data showed 50% ovehead in snmp_fold_field.
reason: currently __snmp6_fill_stats64
[kernel.kallsyms] [k] _raw_spin_lock
Signed-off-by: Raghavendra K T
---
net/ipv6/addrconf.c | 14 +++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 21c2c81..2ec905f 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
Signed-off-by: Raghavendra K T
---
include/net/ip.h | 10 ++
net/ipv4/af_inet.c | 41 +++--
2 files changed, 37 insertions(+), 14 deletions(-)
diff --git a/include/net/ip.h b/include/net/ip.h
index d5fe9f2..93bf12e 100644
--- a/include/net/ip.h
[.] strings.FieldsFunc
2.96% docker docker[.] backtrace_qsort
cache-misses: 1.38 %
Please let me know if you have suggestions/comments.
Raghavendra K T (2):
net:
On 07/15/2015 07:43 AM, Waiman Long wrote:
Performing CPU kicking at lock time can be a bit faster if there
is no kick-ahead. On the other hand, deferring it to unlock time is
preferrable when kick-ahead can be performed or when the VM guest is
having too few vCPUs that a vCPU may be kicked twice
On 06/13/2015 04:05 AM, Waiman Long wrote:
On 06/12/2015 08:31 AM, Stephen Smalley wrote:
On 06/12/2015 02:26 AM, Raghavendra K T wrote:
On 06/12/2015 03:01 AM, Waiman Long wrote:
The inode_free_security() function just took the superblock's isec_lock
before checking and trying to remov
On 06/12/2015 03:01 AM, Waiman Long wrote:
The inode_free_security() function just took the superblock's isec_lock
before checking and trying to remove the inode security struct from the
linked list. In many cases, the list was empty and so the lock taking
is wasteful as no useful work is done. O
On 06/09/2015 01:05 AM, Andrew Morton wrote:
On Sun, 7 Jun 2015 11:41:15 +0530 Raghavendra KT
wrote:
On Tue, May 12, 2015 at 7:04 PM, Vladimir Davydov
wrote:
Hi,
This patch set introduces a new user API for tracking user memory pages
that have not been used for a given period of time. The
On 06/02/2015 11:19 AM, Sarbojit Ganguly wrote:
I made the CONFIG_ARCH_MULTI_V6=y and
CONFIG_CPU_V6K=y
CONFIG_CPU_32v6=y
CONFIG_CPU_32v6K=y
and compiled 4.0.4 with the patch. Result is a compilation success.
Regards,
Sarbojit
Hi Sarbojit,
I am not familiar about the implication of setting t
On 05/05/2015 09:45 AM, Tahsin Erdogan wrote:
A spinlock is regarded as contended when there is at least one waiter.
Currently, the code that checks whether there are any waiters rely on
tail value being greater than head. However, this is not true if tail
reaches the max value and wraps back to
On 05/05/2015 07:33 PM, Tahsin Erdogan wrote:
The conversion to signed happens with types shorter than int (__ticket_t
is either u8 or u16).
By changing Raghavendra's program to use unsigned short int, you can see
the problem:
#include
#define LOCK_INC 2
int main()
{
On 05/05/2015 09:02 PM, Waiman Long wrote:
On 05/05/2015 11:25 AM, Raghavendra K T wrote:
On 05/05/2015 07:33 PM, Tahsin Erdogan wrote:
The conversion to signed happens with types shorter than int (__ticket_t
is either u8 or u16).
By changing Raghavendra's program to use unsigned shor
On 05/05/2015 02:47 PM, Peter Zijlstra wrote:
On Mon, May 04, 2015 at 09:15:31PM -0700, Tahsin Erdogan wrote:
A spinlock is regarded as contended when there is at least one waiter.
Currently, the code that checks whether there are any waiters rely on
tail value being greater than head. However,
of patches works fine.
Feel free to add
Tested-by: Raghavendra K T #kvm pv
As far as performance is concerned (with my 16core +ht machine having
16vcpu guests [ even w/ , w/o the lfsr hash patchset ]), I do not see
any significant observations to report, though I understand that we
could see much
On 03/20/2015 02:38 AM, Waiman Long wrote:
On 03/19/2015 06:01 AM, Peter Zijlstra wrote:
[...]
You are probably right. The initial apply_paravirt() was done before the
SMP boot. Subsequent ones were at kernel module load time. I put a
counter in the __native_queue_spin_unlock() and it registere
On 02/24/2015 08:50 PM, Greg KH wrote:
On Tue, Feb 24, 2015 at 03:47:37PM +0100, Ingo Molnar wrote:
* Greg KH wrote:
On Tue, Feb 24, 2015 at 02:54:59PM +0530, Raghavendra K T wrote:
Paravirt spinlock clears slowpath flag after doing unlock.
As explained by Linus currently it does
On 02/24/2015 08:17 PM, Ingo Molnar wrote:
* Greg KH wrote:
On Tue, Feb 24, 2015 at 02:54:59PM +0530, Raghavendra K T wrote:
Paravirt spinlock clears slowpath flag after doing unlock.
As explained by Linus currently it does:
prev = *lock;
add_smp(&
0.02
dbench 1x -1.77
dbench 2x -0.63
[Jeremy: hinted missing TICKET_LOCK_INC for kick]
[Oleg: Moving slowpath flag to head, ticket_equals idea]
[PeterZ: Detailed changelog]
Reported-by: Sasha Levin
Suggested-by: Linus Torvalds
Signed-off-by: Raghavendra K T
Review
Commit-ID: d6abfdb2022368d8c6c4be3f11a06656601a6cc2
Gitweb: http://git.kernel.org/tip/d6abfdb2022368d8c6c4be3f11a06656601a6cc2
Author: Raghavendra K T
AuthorDate: Fri, 6 Feb 2015 16:44:11 +0530
Committer: Ingo Molnar
CommitDate: Wed, 18 Feb 2015 14:53:49 +0100
x86/spinlocks/paravirt
On 02/16/2015 10:17 PM, David Vrabel wrote:
On 15/02/15 17:30, Raghavendra K T wrote:
--- a/arch/x86/xen/spinlock.c
+++ b/arch/x86/xen/spinlock.c
@@ -41,7 +41,7 @@ static u8 zero_stats;
static inline void check_zero(void)
{
u8 ret;
- u8 old = ACCESS_ONCE(zero_stats
On 02/15/2015 09:47 PM, Oleg Nesterov wrote:
Well, I regret I mentioned the lack of barrier after enter_slowpath ;)
On 02/15, Raghavendra K T wrote:
@@ -46,7 +46,8 @@ static __always_inline bool static_key_false(struct
static_key *key);
static inline void __ticket_enter_slowpath
* Raghavendra K T [2015-02-15 11:25:44]:
Resending the V5 with smp_mb__after_atomic() change without bumping up
revision
---8<---
>From 0b9ecde30e3bf5b5b24009fd2ac5fc7ac4b81158 Mon Sep 17 00:00:00 2001
From: Raghavendra K T
Date: Fri, 6 Feb 2015 16:44:11 +0530
Subject: [PATCH RESEND V
On 02/15/2015 11:25 AM, Raghavendra K T wrote:
Paravirt spinlock clears slowpath flag after doing unlock.
As explained by Linus currently it does:
prev = *lock;
add_smp(&lock->tickets.head, TICKET_LOCK_INC);
/* add_smp() is a
0.02
dbench 1x -1.77
dbench 2x -0.63
[Jeremy: hinted missing TICKET_LOCK_INC for kick]
[Oleg: Moving slowpath flag to head, ticket_equals idea]
[PeterZ: Detailed changelog]
Reported-by: Sasha Levin
Suggested-by: Linus Torvalds
Signed-off-by: Raghavendra K
On 02/13/2015 09:02 PM, Oleg Nesterov wrote:
On 02/13, Raghavendra K T wrote:
@@ -164,7 +161,7 @@ static inline int arch_spin_is_locked(arch_spinlock_t *lock)
{
struct __raw_tickets tmp = READ_ONCE(lock->tickets);
- return tmp.tail != tmp.head;
+ return tmp.t
0.02
dbench 1x -1.77
dbench 2x -0.63
[Jeremy: hinted missing TICKET_LOCK_INC for kick]
[Oleg: Moving slowpath flag to head, ticket_equals idea]
[PeterZ: Detailed changelog]
Reported-by: Sasha Levin
Suggested-by: Linus Torvalds
Signed-off-by: Raghavendra K
On 02/12/2015 08:30 PM, Peter Zijlstra wrote:
On Thu, Feb 12, 2015 at 05:17:27PM +0530, Raghavendra K T wrote:
[...]
Linus suggested that we should not do any writes to lock after unlock(),
and we can move slowpath clearing to fastpath lock.
So this patch implements the fix with:
1. Moving
On 02/12/2015 07:32 PM, Oleg Nesterov wrote:
Damn, sorry for noise, forgot to mention...
On 02/12, Raghavendra K T wrote:
+static inline void __ticket_check_and_clear_slowpath(arch_spinlock_t *lock,
+ __ticket_t head)
+{
+ if (head
On 02/12/2015 07:20 PM, Oleg Nesterov wrote:
On 02/12, Raghavendra K T wrote:
@@ -191,8 +189,7 @@ static inline void arch_spin_unlock_wait(arch_spinlock_t
*lock)
* We need to check "unlocked" in a loop, tmp.head == head
* can be false positive
On 02/12/2015 07:07 PM, Oleg Nesterov wrote:
On 02/12, Raghavendra K T wrote:
@@ -772,7 +773,8 @@ __visible void kvm_lock_spinning(struct arch_spinlock
*lock, __ticket_t want)
* check again make sure it didn't become free while
* we weren't looking.
*/
x -0.63
[Jeremy: hinted missing TICKET_LOCK_INC for kick]
[Oleg: Moving slowpath flag to head, ticket_equals idea]
Reported-by: Sasha Levin
Suggested-by: Linus Torvalds
Signed-off-by: Raghavendra K T
---
arch/x86/include/asm/spinlock.h | 87 -
ar
On 02/11/2015 11:08 PM, Oleg Nesterov wrote:
On 02/11, Raghavendra K T wrote:
On 02/10/2015 06:56 PM, Oleg Nesterov wrote:
In this case __ticket_check_and_clear_slowpath() really needs to cmpxchg
the whole .head_tail. Plus obviously more boring changes. This needs a
separate patch even _if_
On 02/10/2015 06:56 PM, Oleg Nesterov wrote:
On 02/10, Raghavendra K T wrote:
On 02/10/2015 06:23 AM, Linus Torvalds wrote:
add_smp(&lock->tickets.head, TICKET_LOCK_INC);
if (READ_ONCE(lock->tickets.tail) & TICKET_SLOWPATH_FLAG) ..
into something like
On 02/10/2015 06:23 AM, Linus Torvalds wrote:
On Mon, Feb 9, 2015 at 4:02 AM, Peter Zijlstra wrote:
On Mon, Feb 09, 2015 at 03:04:22PM +0530, Raghavendra K T wrote:
So we have 3 choices,
1. xadd
2. continue with current approach.
3. a read before unlock and also after that.
For the truly
Ccing Davidlohr, (sorry that I got confused with similar address in cc
list).
On 02/09/2015 08:44 PM, Oleg Nesterov wrote:
On 02/09, Raghavendra K T wrote:
+static inline void __ticket_check_and_clear_slowpath(arch_spinlock_t *lock)
+{
+ arch_spinlock_t old, new;
+ __ticket_t diff
ll
could be set when somebody does arch_trylock. Handle that too by ignoring
slowpath flag during lock availability check.
[Jeremy: hinted missing TICKET_LOCK_INC for kick]
Reported-by: Sasha Levin
Suggested-by: Linus Torvalds
Signed-off-by: Raghavendra K T
---
ar
On 02/09/2015 05:32 PM, Peter Zijlstra wrote:
On Mon, Feb 09, 2015 at 03:04:22PM +0530, Raghavendra K T wrote:
So we have 3 choices,
1. xadd
2. continue with current approach.
3. a read before unlock and also after that.
For the truly paranoid we have probe_kernel_address(), suppose the lock
On 02/09/2015 02:44 AM, Jeremy Fitzhardinge wrote:
On 02/06/2015 06:49 AM, Raghavendra K T wrote:
[...]
Linus suggested that we should not do any writes to lock after unlock(),
and we can move slowpath clearing to fastpath lock.
Yep, that seems like a sound approach.
Current approach
On 02/07/2015 12:27 AM, Sasha Levin wrote:
On 02/06/2015 09:49 AM, Raghavendra K T wrote:
Paravirt spinlock clears slowpath flag after doing unlock.
As explained by Linus currently it does:
prev = *lock;
add_smp(&lock->tickets.head, TICKET_L
On 02/06/2015 09:55 PM, Linus Torvalds wrote:
On Fri, Feb 6, 2015 at 6:49 AM, Raghavendra K T
wrote:
Paravirt spinlock clears slowpath flag after doing unlock.
[ fix edited out ]
So I'm not going to be applying this for 3.19, because it's much too
late and the patch is too scary
On 02/06/2015 12:18 PM, Raghavendra K T wrote:
On 02/06/2015 04:27 AM, Linus Torvalds wrote:
On Thu, Feb 5, 2015 at 2:37 PM, Davidlohr Bueso
wrote:
It is possible that the paravirt spinlocks could be saved by:
- moving the clearing of TICKET_SLOWPATH_FLAG into the fastpath
locking code
ll
could be set when somebody does arch_trylock. Handle that too by ignoring
slowpath flag during lock availability check.
Reported-by: Sasha Levin
Suggested-by: Linus Torvalds
Signed-off-by: Raghavendra K T
---
arch/x86/include/asm/spinlock.h | 70 -
1 file chang
On 02/06/2015 04:07 AM, Davidlohr Bueso wrote:
On Thu, 2015-02-05 at 13:34 -0800, Linus Torvalds wrote:
On Thu, Feb 5, 2015 at 1:02 PM, Sasha Levin wrote:
Interestingly enough, according to that article this behaviour seems to be
"by design":
Oh, it's definitely by design, it's just that th
On 02/06/2015 04:27 AM, Linus Torvalds wrote:
On Thu, Feb 5, 2015 at 2:37 PM, Davidlohr Bueso wrote:
It is possible that the paravirt spinlocks could be saved by:
- moving the clearing of TICKET_SLOWPATH_FLAG into the fastpath locking code.
Ouch, to avoid deadlocks they explicitly need th
On 01/21/2015 01:42 AM, Waiman Long wrote:
This patch renames the paravirt_ticketlocks_enabled static key to a
more generic paravirt_spinlocks_enabled name.
Signed-off-by: Waiman Long
Signed-off-by: Peter Zijlstra
---
Reviewed-by: Raghavendra K T
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On 10/09/2014 10:42 AM, Preeti U Murthy wrote:
Hi Raghu,
remove_tasks_in_empty_cpuset() is called on the legacy hierarchy when
the cpuset becomes empty, hence we require it. But you are right its not
called on the default hierarchy.
My point was if legacy hierarchy follows unified hierarchy
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