From: Andrew Morton <akpm@linux-foundation.org>
To: Rik van Riel <riel@redhat.com>
Cc: Randy Dunlap <rdunlap@xenotime.net>,
Satoru Moriya <smoriya@redhat.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
lwoodman@redhat.com, Seiji Aguchi <saguchi@redhat.com>,
hughd@google.com, hannes@cmpxchg.org
Subject: Re: [PATCH -v2 -mm] add extra free kbytes tunable
Date: Thu, 1 Sep 2011 15:09:01 -0700 [thread overview]
Message-ID: <20110901150901.48d92bc2.akpm@linux-foundation.org> (raw)
In-Reply-To: <20110901152650.7a63cb8b@annuminas.surriel.com>
On Thu, 1 Sep 2011 15:26:50 -0400
Rik van Riel <riel@redhat.com> wrote:
> Add a userspace visible knob to tell the VM to keep an extra amount
> of memory free, by increasing the gap between each zone's min and
> low watermarks.
>
> This is useful for realtime applications that call system
> calls and have a bound on the number of allocations that happen
> in any short time period. In this application, extra_free_kbytes
> would be left at an amount equal to or larger than than the
> maximum number of allocations that happen in any burst.
>
> It may also be useful to reduce the memory use of virtual
> machines (temporarily?), in a way that does not cause memory
> fragmentation like ballooning does.
>
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -96,6 +96,7 @@ extern char core_pattern[];
> extern unsigned int core_pipe_limit;
> extern int pid_max;
> extern int min_free_kbytes;
> +extern int extra_free_kbytes;
No externs in C, please. Feel free to fix min_free_kbytes while you're
there ;)
swap.h is a common place to declare these things. mmzone.h would make
sense too.
> extern int pid_max_min, pid_max_max;
> extern int sysctl_drop_caches;
> extern int percpu_pagelist_fraction;
> @@ -1189,6 +1190,14 @@ static struct ctl_table vm_table[] = {
> .extra1 = &zero,
> },
> {
> + .procname = "extra_free_kbytes",
> + .data = &extra_free_kbytes,
> + .maxlen = sizeof(extra_free_kbytes),
> + .mode = 0644,
> + .proc_handler = min_free_kbytes_sysctl_handler,
Lazy. The function should be renamed to accurately reflect its role.
> + .extra1 = &zero,
> + },
> + {
> .procname = "percpu_pagelist_fraction",
> .data = &percpu_pagelist_fraction,
> .maxlen = sizeof(percpu_pagelist_fraction),
>
> ...
>
> +int extra_free_kbytes = 0;
I'm inclined to agree with checkpatch here - it's just noise.
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next prev parent reply other threads:[~2011-09-01 22:09 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 [this message]
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
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
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