From: Rik van Riel <riel@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Satoru Moriya <satoru.moriya@hds.com>,
David Rientjes <rientjes@google.com>,
Randy Dunlap <rdunlap@xenotime.net>,
Satoru Moriya <smoriya@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"lwoodman@redhat.com" <lwoodman@redhat.com>,
Seiji Aguchi <saguchi@redhat.com>,
"hughd@google.com" <hughd@google.com>,
"hannes@cmpxchg.org" <hannes@cmpxchg.org>
Subject: Re: [PATCH -v2 -mm] add extra free kbytes tunable
Date: Wed, 12 Oct 2011 15:58:31 -0400 [thread overview]
Message-ID: <4E95F167.5050709@redhat.com> (raw)
In-Reply-To: <20111012122018.690bdf28.akpm@linux-foundation.org>
On 10/12/2011 03:20 PM, Andrew Morton wrote:
> On Wed, 12 Oct 2011 09:09:17 -0400
> Rik van Riel<riel@redhat.com> wrote:
>> The problem is that we may be dealing with bursts, not steady
>> states of allocations. Without knowing the size of a burst,
>> we have no idea when we should wake up kswapd to get enough
>> memory freed ahead of the application's allocations.
>
> That problem remains with this patch - it just takes a larger burst.
>
> Unless the admin somehow manages to configure the tunable large enough
> to cover the largest burst, and there aren't other applications
> allocating memory during that burst, and the time between bursts is
> sufficient for kswapd to be able to sufficiently replenish free-page
> reserves. All of which sounds rather unlikely.
It depends on the system. For a setup which is packed to
the brim with workloads, this patch is not likely to help.
On the other hand, on a system that is packed to the brim
with workloads, you are unlikely to get low latencies anyway.
For situations where people really care about low latencies,
I imagine having dedicated hardware for a workload is not at
all unusual, and the patch works for that.
>>> Look, please don't go bending over backwards like this to defend a bad
>>> patch. It's a bad patch! It would be better not to have to merge it.
>>> Let's do something better.
>>
>> I would love it if we could come up with something better,
>> and have thought about it a lot.
>>
>> However, so far we do not seem to have an alternative yet :(
>
> Do we actually have a real-world application which is hurting from
> this?
Satoru-san?
--
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/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2011-10-12 19:58 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-01 14:52 [PATCH -mm] add extra free kbytes tunable Rik van Riel
2011-09-01 17:06 ` Randy Dunlap
2011-09-01 19:26 ` [PATCH -v2 " Rik van Riel
2011-09-01 21:58 ` Andrew Morton
2011-09-01 22:08 ` David Rientjes
2011-09-01 22:16 ` Andrew Morton
2011-09-02 16:31 ` Satoru Moriya
2011-10-13 7:33 ` Minchan Kim
2011-10-13 8:09 ` KAMEZAWA Hiroyuki
[not found] ` <E1FA588BC672D846BDBB452FCA1E308C2389B4@USINDEVS02.corp.hds.com>
2011-09-15 3:33 ` Satoru Moriya
2011-09-01 22:09 ` Andrew Morton
2011-09-02 16:26 ` [PATCH -mm] fixes & cleanups for "add extra free kbytes tunable" Rik van Riel
2011-09-30 21:43 ` [PATCH -v2 -mm] add extra free kbytes tunable Johannes Weiner
2011-10-08 3:08 ` David Rientjes
2011-10-10 22:37 ` Andrew Morton
2011-10-11 19:32 ` Satoru Moriya
2011-10-11 19:54 ` Andrew Morton
2011-10-11 20:23 ` Satoru Moriya
2011-10-11 20:54 ` Andrew Morton
2011-10-12 13:09 ` Rik van Riel
2011-10-12 19:20 ` Andrew Morton
2011-10-12 19:58 ` Rik van Riel [this message]
2011-10-12 20:26 ` David Rientjes
2011-10-21 23:48 ` Satoru Moriya
2011-10-23 21:22 ` David Rientjes
2011-10-25 2:04 ` Satoru Moriya
2011-10-25 21:50 ` David Rientjes
2011-10-26 18:59 ` Satoru Moriya
2011-10-12 21:08 ` Satoru Moriya
2011-10-12 22:41 ` David Rientjes
2011-10-12 23:52 ` Satoru Moriya
2011-10-13 0:01 ` David Rientjes
2011-10-13 5:35 ` KAMEZAWA Hiroyuki
2011-10-13 20:55 ` David Rientjes
2011-10-14 22:16 ` Satoru Moriya
2011-10-14 22:46 ` David Rientjes
2011-10-14 5:32 ` Satoru Moriya
2011-10-14 5:06 ` Satoru Moriya
2011-10-11 23:22 ` David Rientjes
2011-10-13 16:54 ` Satoru Moriya
2011-10-13 20:48 ` David Rientjes
2011-10-13 21:11 ` Rik van Riel
2011-10-13 22:02 ` David Rientjes
2011-10-11 19:20 ` Satoru Moriya
2011-10-11 21:04 ` David Rientjes
2011-10-12 13:13 ` Rik van Riel
2011-10-12 20:21 ` David Rientjes
2011-10-13 4:13 ` Rik van Riel
2011-10-13 5:22 ` David Rientjes
2011-10-22 0:11 ` Satoru Moriya
-- strict thread matches above, loose matches on Subject: below --
2011-09-09 23:01 Satoru Moriya
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=4E95F167.5050709@redhat.com \
--to=riel@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=hannes@cmpxchg.org \
--cc=hughd@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=lwoodman@redhat.com \
--cc=rdunlap@xenotime.net \
--cc=rientjes@google.com \
--cc=saguchi@redhat.com \
--cc=satoru.moriya@hds.com \
--cc=smoriya@redhat.com \
/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).