From: Mel Gorman <mgorman@techsingularity.net>
To: Roman Gushchin <guro@fb.com>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@suse.com>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
Rik van Riel <riel@redhat.com>,
kernel-team@fb.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: make allocation counters per-order
Date: Thu, 6 Jul 2017 14:19:41 +0100 [thread overview]
Message-ID: <20170706131941.omod4zl4cyuscmjo@techsingularity.net> (raw)
In-Reply-To: <1499346271-15653-1-git-send-email-guro@fb.com>
On Thu, Jul 06, 2017 at 02:04:31PM +0100, Roman Gushchin wrote:
> High-order allocations are obviously more costly, and it's very useful
> to know how many of them happens, if there are any issues
> (or suspicions) with memory fragmentation.
>
> This commit changes existing per-zone allocation counters to be
> per-zone per-order. These counters are displayed using a new
> procfs interface (similar to /proc/buddyinfo):
>
> $ cat /proc/allocinfo
> DMA 0 0 0 0 0 \
> 0 0 0 0 0 0
> DMA32 3 0 1 0 0 \
> 0 0 0 0 0 0
> Normal 4997056 23594 10902 23686 931 \
> 23 122 786 17 1 0
> Movable 0 0 0 0 0 \
> 0 0 0 0 0 0
> Device 0 0 0 0 0 \
> 0 0 0 0 0 0
>
> The existing vmstat interface remains untouched*, and still shows
> the total number of single page allocations, so high-order allocations
> are represented as a corresponding number of order-0 allocations.
>
> $ cat /proc/vmstat | grep alloc
> pgalloc_dma 0
> pgalloc_dma32 7
> pgalloc_normal 5461660
> pgalloc_movable 0
> pgalloc_device 0
>
> * I've added device zone for consistency with other zones,
> and to avoid messy exclusion of this zone in the code.
>
The alloc counter updates are themselves a surprisingly heavy cost to
the allocation path and this makes it worse for a debugging case that is
relatively rare. I'm extremely reluctant for such a patch to be added
given that the tracepoints can be used to assemble such a monitor even
if it means running a userspace daemon to keep track of it. Would such a
solution be suitable? Failing that if this is a severe issue, would it be
possible to at least make this a compile-time or static tracepoint option?
That way, only people that really need it have to take the penalty.
--
Mel Gorman
SUSE Labs
--
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:[~2017-07-06 13:19 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-06 13:04 [PATCH] mm: make allocation counters per-order Roman Gushchin
2017-07-06 13:19 ` Mel Gorman [this message]
2017-07-06 14:46 ` Roman Gushchin
2017-07-06 15:47 ` Mel Gorman
2017-07-06 16:43 ` Roman Gushchin
2017-07-06 17:16 ` Mel Gorman
2017-07-06 18:00 ` Debabrata Banerjee
2017-07-06 20:02 ` Mel Gorman
2017-07-16 13:27 ` Roman Gushchin
2017-07-16 13:29 ` Roman Gushchin
2017-07-16 13:55 ` [v2] " kbuild test robot
2017-07-06 14:54 ` [PATCH] " Debabrata Banerjee
2017-07-06 15:51 ` Mel Gorman
2017-07-06 16:12 ` Debabrata Banerjee
2017-07-06 16:43 ` Mel Gorman
2017-07-06 15:02 ` Christoph Lameter
2017-07-07 1:54 ` kbuild test robot
2017-07-07 6:06 ` kbuild test robot
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=20170706131941.omod4zl4cyuscmjo@techsingularity.net \
--to=mgorman@techsingularity.net \
--cc=akpm@linux-foundation.org \
--cc=guro@fb.com \
--cc=hannes@cmpxchg.org \
--cc=kernel-team@fb.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@suse.com \
--cc=riel@redhat.com \
--cc=vdavydov.dev@gmail.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).