From: Minchan Kim <minchan@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Subject: Re: needed lru_add_drain_all() change
Date: Wed, 27 Jun 2012 10:20:24 +0900 [thread overview]
Message-ID: <4FEA5FD8.9060806@kernel.org> (raw)
In-Reply-To: <20120626181504.23b8b73d.akpm@linux-foundation.org>
Hi Andrew,
On 06/27/2012 10:15 AM, Andrew Morton wrote:
> On Wed, 27 Jun 2012 09:55:10 +0900 Minchan Kim <minchan@kernel.org> wrote:
>
>> On 06/27/2012 06:37 AM, Andrew Morton wrote:
>>
>>> https://bugzilla.kernel.org/show_bug.cgi?id=43811
>>>
>>> lru_add_drain_all() uses schedule_on_each_cpu(). But
>>> schedule_on_each_cpu() hangs if a realtime thread is spinning, pinned
>>> to a CPU. There's no intention to change the scheduler behaviour, so I
>>> think we should remove schedule_on_each_cpu() from the kernel.
>>>
>>> The biggest user of schedule_on_each_cpu() is lru_add_drain_all().
>>>
>>> Does anyone have any thoughts on how we can do this? The obvious
>>> approach is to declare these:
>>>
>>> static DEFINE_PER_CPU(struct pagevec[NR_LRU_LISTS], lru_add_pvecs);
>>> static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
>>> static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs);
>>
>>
>> One more
>> static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs);
>>
>>>
>>> to be irq-safe and use on_each_cpu(). lru_rotate_pvecs is already
>>> irq-safe and converting lru_add_pvecs and lru_deactivate_pvecs looks
>>> pretty simple.
>>
>>
>> Yes. Changing looks simple.
>> I'm okay with lru_[activate_page|deactivate]_pvecs because it's not hot
>> but lru_rotate_pvecs is hotter than others.
>
> I don't think any change is needed for lru_rotate_pvecs?
Sorry for the typo
lru_add_pvecs
>
>> Considering mlock and CPU pinning
>> of realtime thread is very rare, it might be rather expensive solution.
>> Unfortunately, I have no idea better than you suggested. :(
>>
>> And looking 8891d6da17, mlock's lru_add_drain_all isn't must.
>> If it's really bother us, couldn't we remove it?
>
> "grep lru_add_drain_all mm/*.c". They're all problematic.
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org. For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
>
--
Kind regards,
Minchan Kim
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2012-06-27 1:20 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-26 21:37 needed lru_add_drain_all() change Andrew Morton
2012-06-27 0:55 ` Minchan Kim
2012-06-27 1:15 ` Andrew Morton
2012-06-27 1:20 ` Minchan Kim [this message]
2012-06-27 1:29 ` Andrew Morton
2012-06-27 2:09 ` Minchan Kim
2012-06-27 5:12 ` Andrew Morton
2012-06-27 5:41 ` Minchan Kim
2012-06-27 5:55 ` Andrew Morton
2012-06-27 6:33 ` Minchan Kim
2012-06-27 6:41 ` Andrew Morton
2012-06-27 10:27 ` Peter Zijlstra
2012-06-27 6:46 ` Andrew Morton
2012-06-27 10:31 ` Peter Zijlstra
2012-06-27 12:04 ` Peter Zijlstra
2012-06-28 6:23 ` KOSAKI Motohiro
2012-06-29 3:47 ` Kamezawa Hiroyuki
2012-06-28 7:43 ` Kamezawa Hiroyuki
2012-06-28 23:42 ` Minchan Kim
2012-06-29 3:24 ` Kamezawa Hiroyuki
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=4FEA5FD8.9060806@kernel.org \
--to=minchan@kernel.org \
--cc=akpm@linux-foundation.org \
--cc=kosaki.motohiro@gmail.com \
--cc=linux-mm@kvack.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).