From: Andrey Ryabinin <aryabinin@virtuozzo.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Thomas Hellstrom <thellstrom@vmware.com>,
<akpm@linux-foundation.org>, <penguin-kernel@I-love.SAKURA.ne.jp>,
<linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>,
<hpa@zytor.com>, <chris@chris-wilson.co.uk>, <hch@lst.de>,
<mingo@elte.hu>, <jszhang@marvell.com>, <joelaf@google.com>,
<joaodias@google.com>, <willy@infradead.org>,
<tglx@linutronix.de>, <stable@vger.kernel.org>
Subject: Re: [PATCH 1/4] mm/vmalloc: allow to call vfree() in atomic context
Date: Wed, 5 Apr 2017 13:31:23 +0300 [thread overview]
Message-ID: <d28bc808-0aab-d36a-f401-9925680fd131@virtuozzo.com> (raw)
In-Reply-To: <20170404094148.GJ15132@dhcp22.suse.cz>
On 04/04/2017 12:41 PM, Michal Hocko wrote:
> On Thu 30-03-17 17:48:39, Andrey Ryabinin wrote:
>> From: Andrey Ryabinin <aryabinin@virtuozzo.com>
>> Subject: mm/vmalloc: allow to call vfree() in atomic context fix
>>
>> Don't spawn worker if we already purging.
>>
>> Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
>
> I would rather put this into a separate patch. Ideally with some numners
> as this is an optimization...
>
It's quite simple optimization and don't think that this deserves to be a separate patch.
But I did some measurements though. With enabled VMAP_STACK=y and NR_CACHED_STACK changed to 0
running fork() 100000 times gives this:
With optimization:
~ # grep try_purge /proc/kallsyms
ffffffff811d0dd0 t try_purge_vmap_area_lazy
~ # perf stat --repeat 10 -ae workqueue:workqueue_queue_work --filter 'function == 0xffffffff811d0dd0' ./fork
Performance counter stats for 'system wide' (10 runs):
15 workqueue:workqueue_queue_work ( +- 0.88% )
1.615368474 seconds time elapsed ( +- 0.41% )
Without optimization:
~ # grep try_purge /proc/kallsyms
ffffffff811d0dd0 t try_purge_vmap_area_lazy
~ # perf stat --repeat 10 -ae workqueue:workqueue_queue_work --filter 'function == 0xffffffff811d0dd0' ./fork
Performance counter stats for 'system wide' (10 runs):
30 workqueue:workqueue_queue_work ( +- 1.31% )
1.613231060 seconds time elapsed ( +- 0.38% )
So there is no measurable difference on the test itself, but we queue twice more jobs without this optimization.
It should decrease load of kworkers.
>> ---
>> mm/vmalloc.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
>> index ea1b4ab..88168b8 100644
>> --- a/mm/vmalloc.c
>> +++ b/mm/vmalloc.c
>> @@ -737,7 +737,8 @@ static void free_vmap_area_noflush(struct vmap_area *va)
>> /* After this point, we may free va at any time */
>> llist_add(&va->purge_list, &vmap_purge_list);
>>
>> - if (unlikely(nr_lazy > lazy_max_pages()))
>> + if (unlikely(nr_lazy > lazy_max_pages()) &&
>> + !mutex_is_locked(&vmap_purge_lock))
>> schedule_work(&purge_vmap_work);
>> }
>>
>> --
>> 2.10.2
>>
>
next prev parent reply other threads:[~2017-04-05 10:31 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-30 10:27 [PATCH 1/4] mm/vmalloc: allow to call vfree() in atomic context Andrey Ryabinin
2017-03-30 10:27 ` [PATCH 2/4] x86/ldt: use vfree() instead of vfree_atomic() Andrey Ryabinin
2017-03-31 8:05 ` Thomas Gleixner
2017-03-30 10:27 ` [PATCH 3/4] kernel/fork: use vfree() instead of vfree_atomic() to free thread stack Andrey Ryabinin
2017-03-30 10:27 ` [PATCH 4/4] mm/vmalloc: remove vfree_atomic() Andrey Ryabinin
2017-03-30 17:18 ` Matthew Wilcox
2017-03-30 15:27 ` Andrey Ryabinin
2017-04-04 9:40 ` Michal Hocko
2017-03-30 12:00 ` [PATCH 1/4] mm/vmalloc: allow to call vfree() in atomic context Thomas Hellstrom
2017-03-30 14:48 ` Andrey Ryabinin
2017-03-30 15:04 ` Thomas Hellstrom
2017-04-04 9:41 ` Michal Hocko
2017-04-04 9:49 ` Thomas Hellstrom
2017-04-05 10:31 ` Andrey Ryabinin [this message]
2017-04-05 10:42 ` Michal Hocko
2017-04-05 11:42 ` Vlastimil Babka
2017-04-05 12:14 ` Michal Hocko
2017-03-30 22:22 ` Andrew Morton
2017-03-31 7:12 ` Joel Fernandes
2017-03-31 9:26 ` Andrey Ryabinin
2017-04-04 9:36 ` Michal Hocko
2017-04-04 9:38 ` Michal Hocko
2017-04-12 12:49 ` [PATCH v2 0/5] " Andrey Ryabinin
2017-04-12 12:49 ` [PATCH v2 1/5] mm/vmalloc: " Andrey Ryabinin
2017-04-12 12:49 ` [PATCH v2 2/5] x86/ldt: use vfree() instead of vfree_atomic() Andrey Ryabinin
2017-04-12 12:49 ` [PATCH v2 3/5] kernel/fork: use vfree() instead of vfree_atomic() to free thread stack Andrey Ryabinin
2017-04-12 12:49 ` [PATCH v2 4/5] mm/vmalloc: remove vfree_atomic() Andrey Ryabinin
2017-04-12 12:49 ` [PATCH v2 5/5] mm/vmalloc: Don't spawn workers if somebody already purging Andrey Ryabinin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=d28bc808-0aab-d36a-f401-9925680fd131@virtuozzo.com \
--to=aryabinin@virtuozzo.com \
--cc=akpm@linux-foundation.org \
--cc=chris@chris-wilson.co.uk \
--cc=hch@lst.de \
--cc=hpa@zytor.com \
--cc=joaodias@google.com \
--cc=joelaf@google.com \
--cc=jszhang@marvell.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@kernel.org \
--cc=mingo@elte.hu \
--cc=penguin-kernel@I-love.SAKURA.ne.jp \
--cc=stable@vger.kernel.org \
--cc=tglx@linutronix.de \
--cc=thellstrom@vmware.com \
--cc=willy@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).