On Tue, Apr 14, 2009 at 03:09:29PM -0700, Andrew Morton wrote:
We need a comment here explaining why we can't use the much preferable
lock_page().
Why can't we use the much preferable lock_page()?
We might but then it'd risk to waste time waiting. It's not worth
waiting, we want kksmd to be
On Wed, Apr 15, 2009 at 05:43:03PM -0700, Jeremy Fitzhardinge wrote:
Shouldn't that be kmap_atomic's job anyway? Otherwise it would be hard to
No because those are full noops in no-highmem kernels. I commented in
other email why I think it's safe thanks to the wrprotect + smp tlb
flush of the
Andrea Arcangeli wrote:
On Wed, Apr 15, 2009 at 05:43:03PM -0700, Jeremy Fitzhardinge wrote:
Shouldn't that be kmap_atomic's job anyway? Otherwise it would be hard to
No because those are full noops in no-highmem kernels. I commented in
other email why I think it's safe thanks to the
Andrew Morton wrote:
On Thu, 9 Apr 2009 06:58:41 +0300
Izik Eidus iei...@redhat.com wrote:
Confused. In the covering email you indicated that v2 of the patchset
had abandoned ioctls and had moved the interface to sysfs.
We have abandoned the ioctls that control the ksm behavior (how
On Thu, 16 Apr 2009 01:37:25 +0300
Izik Eidus iei...@redhat.com wrote:
Andrew Morton wrote:
On Thu, 9 Apr 2009 06:58:41 +0300
Izik Eidus iei...@redhat.com wrote:
Confused. In the covering email you indicated that v2 of the patchset
had abandoned ioctls and had moved the
On Wed, Apr 15, 2009 at 03:50:58PM -0700, Andrew Morton wrote:
an optional thing and can even be modprobed, that doesn't work. And
having a driver in mm/ which can be modprobed is kinda neat.
Agreed. I think madvise with all its vma split requirements and
ksm-unregistering invoked at vma
Andrew Morton wrote:
+static pte_t *get_pte(struct mm_struct *mm, unsigned long addr)
+{
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *ptep = NULL;
+
+ pgd = pgd_offset(mm, addr);
+ if (!pgd_present(*pgd))
+ goto out;
+
+ pud =
Jeremy Fitzhardinge wrote:
Andrew Morton wrote:
+static pte_t *get_pte(struct mm_struct *mm, unsigned long addr)
+{
+pgd_t *pgd;
+pud_t *pud;
+pmd_t *pmd;
+pte_t *ptep = NULL;
+
+pgd = pgd_offset(mm, addr);
+if (!pgd_present(*pgd))
+goto out;
+
+pud =
On Thu, 9 Apr 2009 06:58:41 +0300
Izik Eidus iei...@redhat.com wrote:
Ksm is driver that allow merging identical pages between one or more
applications in way unvisible to the application that use it.
Pages that are merged are marked as readonly and are COWed when any
application try to
Ksm is driver that allow merging identical pages between one or more
applications in way unvisible to the application that use it.
Pages that are merged are marked as readonly and are COWed when any
application try to change them.
Ksm is used for cases where using fork() is not suitable,
one of
Andrey Panin wrote:
On 094, 04 04, 2009 at 05:35:22PM +0300, Izik Eidus wrote:
SNIP
+static inline u32 calc_checksum(struct page *page)
+{
+ u32 checksum;
+ void *addr = kmap_atomic(page, KM_USER0);
+ checksum = jhash(addr, PAGE_SIZE, 17);
Why jhash2() is not used
Ksm is driver that allow merging identical pages between one or more
applications in way unvisible to the application that use it.
Pages that are merged are marked as readonly and are COWed when any
application try to change them.
Ksm is used for cases where using fork() is not suitable,
one of
Anthony Liguori wrote:
I'm often afraid of what sort of bugs we'd uncover in kvm if we passed
the fds around via SCM_RIGHTS and started poking around :-/
kvm checks the mm doesn't change underneath.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to
On Wed, Apr 01, 2009 at 09:36:31PM -0500, Anthony Liguori wrote:
on this behavior to unregister memory regions, you could potentially have
badness happen in the kernel if ksm attempted to access an invalid memory
region.
How could you possibly come to this conclusion? If badness could ever
Anthony Liguori wrote:
Chris Wright wrote:
* Anthony Liguori (anth...@codemonkey.ws) wrote:
The ioctl() interface is quite bad for what you're doing. You're
telling the kernel extra information about a VA range in
userspace. That's what madvise is for. You're tweaking simple
KAMEZAWA Hiroyuki wrote:
On Tue, 31 Mar 2009 15:21:53 +0300
Izik Eidus iei...@redhat.com wrote:
kpage is actually what going to be KsmPage - the shared page...
Right now this pages are not swappable..., after ksm will be merged we
will make this pages swappable as well...
Anthony Liguori wrote:
Andrea Arcangeli wrote:
On Tue, Mar 31, 2009 at 10:54:57AM -0500, Anthony Liguori wrote:
You can still disable ksm and simply return ENOSYS for the MADV_
flag. You
Anthony, the biggest problem about madvice() is that it is a real system
call api, i wouldnt
Izik Eidus wrote:
Anthony, the biggest problem about madvice() is that it is a real
system call api, i wouldnt want in that stage of ksm commit into api
changes of linux...
The ioctl itself is restricting, madvice is much more...,
Can we draft this issue to after ksm is merged, and after all
* Anthony Liguori (anth...@codemonkey.ws) wrote:
You can't change ABIs after something is merged or you break userspace.
So you need to figure out the right ABI first.
Absolutely.
--
To unsubscribe from this list: send the line unsubscribe kvm in
the body of a message to
* Anthony Liguori (anth...@codemonkey.ws) wrote:
The ioctl() interface is quite bad for what you're doing. You're
telling the kernel extra information about a VA range in userspace.
That's what madvise is for. You're tweaking simple read/write values of
kernel infrastructure. That's
Chris Wright wrote:
* Anthony Liguori (anth...@codemonkey.ws) wrote:
The ioctl() interface is quite bad for what you're doing. You're
telling the kernel extra information about a VA range in userspace.
That's what madvise is for. You're tweaking simple read/write values of
kernel
KAMEZAWA Hiroyuki wrote:
On Tue, 31 Mar 2009 02:59:20 +0300
Izik Eidus iei...@redhat.com wrote:
Ksm is driver that allow merging identical pages between one or more
applications in way unvisible to the application that use it.
Pages that are merged are marked as readonly and are COWed when
Anthony Liguori wrote:
Izik Eidus wrote:
Ksm is driver that allow merging identical pages between one or more
applications in way unvisible to the application that use it.
Pages that are merged are marked as readonly and are COWed when any
application try to change them.
Ksm is used for cases
Izik Eidus wrote:
I belive using ioctl for registering memory of applications make it
easier
Yes, I completely agree.
Ksm doesnt have any complicated API that would benefit from sysfs
(beside adding more complexity)
That is, the KSM_START_STOP_KTHREAD part, not necessarily the rest
On Tue, Mar 31, 2009 at 08:31:31AM -0500, Anthony Liguori wrote:
You could drop KSM_START_STOP_KTHREAD and KSM_GET_INFO_KTHREAD altogether,
and introduce a sysfs hierarchy:
/sysfs/some/path/ksm/{enable,pages_to_scan,sleep_time}
Introducing a sysfs hierarchy sounds a bit of overkill.
the
Andrea Arcangeli wrote:
the ability to disable KSM. That seems like a security concern to me since
registering a memory region ought to be an unprivileged action whereas
enabling/disabling KSM ought to be a privileged action.
sysfs files would then only be writeable by admin, so if we
On Tue, Mar 31, 2009 at 09:37:17AM -0500, Anthony Liguori wrote:
In the very least, if you insist on not using sysfs, you should have a
separate character device that's used for control (like /dev/ksmctl).
I'm fine to use sysfs that's not the point, if you've to add a ksmctl
device, then sysfs
Andrea Arcangeli wrote:
On Tue, Mar 31, 2009 at 09:37:17AM -0500, Anthony Liguori wrote:
In the very least, if you insist on not using sysfs, you should have a
separate character device that's used for control (like /dev/ksmctl).
I'm fine to use sysfs that's not the point, if you've
On Tue, Mar 31, 2009 at 10:09:24AM -0500, Anthony Liguori wrote:
I don't think the registering of ram should be done via sysfs. That would
be a pretty bad interface IMHO. But I do think the functionality that
ksmctl provides along with the security issues I mentioned earlier really
Andrea Arcangeli wrote:
On Tue, Mar 31, 2009 at 10:09:24AM -0500, Anthony Liguori wrote:
I don't think the registering of ram should be done via sysfs. That would
be a pretty bad interface IMHO. But I do think the functionality that
ksmctl provides along with the security issues I
On Tue, Mar 31, 2009 at 10:54:57AM -0500, Anthony Liguori wrote:
You can still disable ksm and simply return ENOSYS for the MADV_ flag. You
-EINVAL if something, -ENOSYS would tell userland that it shall stop
trying to use madvise, including the other MADV_ too.
could even keep it as a
Andrea Arcangeli wrote:
On Tue, Mar 31, 2009 at 10:54:57AM -0500, Anthony Liguori wrote:
You can still disable ksm and simply return ENOSYS for the MADV_ flag. You
-EINVAL if something, -ENOSYS would tell userland that it shall stop
trying to use madvise, including the other MADV_
On Tue, Mar 31, 2009 at 11:51:14AM -0500, Anthony Liguori wrote:
You have two things here. CONFIG_MEM_SHARABLE and CONFIG_KSM.
CONFIG_MEM_SHARABLE cannot be a module. If it's set to =n, then
madvise(MADV_SHARABLE) == -ENOSYS.
Where the part that -ENOSYS tell userland madvise syscall table
Hello,
I attach below some benchmark of the new ksm tree algorithm, showing
ksm performance in best and worst case scenarios.
---
Here a program ksmpages.c that tries to create the worst case scenario
for the ksm tree algorithm.
On Tue, 31 Mar 2009 15:21:53 +0300
Izik Eidus iei...@redhat.com wrote:
kpage is actually what going to be KsmPage - the shared page...
Right now this pages are not swappable..., after ksm will be merged we
will make this pages swappable as well...
sure.
If so, please
- show the
Ksm is driver that allow merging identical pages between one or more
applications in way unvisible to the application that use it.
Pages that are merged are marked as readonly and are COWed when any
application try to change them.
Ksm is used for cases where using fork() is not suitable,
one of
Izik Eidus wrote:
Ksm is driver that allow merging identical pages between one or more
applications in way unvisible to the application that use it.
Pages that are merged are marked as readonly and are COWed when any
application try to change them.
Ksm is used for cases where using fork() is
On Tue, 31 Mar 2009 02:59:20 +0300
Izik Eidus iei...@redhat.com wrote:
Ksm is driver that allow merging identical pages between one or more
applications in way unvisible to the application that use it.
Pages that are merged are marked as readonly and are COWed when any
application try to
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