From: Hyeonggon Yoo <42.hyeyoo@gmail.com>
To: Vasily Averin <vvs@openvz.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
kernel@openvz.org, linux-kernel@vger.kernel.org,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@redhat.com>,
linux-mm@kvack.org, Shakeel Butt <shakeelb@google.com>,
Roman Gushchin <roman.gushchin@linux.dev>,
Vlastimil Babka <vbabka@suse.cz>,
Matthew Wilcox <willy@infradead.org>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
David Rientjes <rientjes@google.com>,
Pekka Enberg <penberg@kernel.org>,
Christoph Lameter <cl@linux.com>, Michal Hocko <mhocko@suse.com>,
Muchun Song <songmuchun@bytedance.com>
Subject: Re: [PATCH v4] tracing: add 'accounted' entry into output of allocation tracepoints
Date: Sun, 22 May 2022 05:19:20 +0000 [thread overview]
Message-ID: <YonH2AqfEFYKrUV2@n2.us-central1-a.c.spheric-algebra-350919.internal> (raw)
In-Reply-To: <1621d82a-439d-0657-2b7e-5e90c42c2087@openvz.org>
On Sun, May 22, 2022 at 07:33:08AM +0300, Vasily Averin wrote:
> On 5/22/22 06:51, Hyeonggon Yoo wrote:
> > On Sat, May 21, 2022 at 09:36:54PM +0300, Vasily Averin wrote:
> >> Slab caches marked with SLAB_ACCOUNT force accounting for every
> >> allocation from this cache even if __GFP_ACCOUNT flag is not passed.
> >> Unfortunately, at the moment this flag is not visible in ftrace output,
> >> and this makes it difficult to analyze the accounted allocations.
> >>
> >> This patch adds boolean "accounted" entry into trace output,
> >> and set it to 'true' for calls used __GFP_ACCOUNT flag and
> >> for allocations from caches marked with SLAB_ACCOUNT.
> >>
> >> Signed-off-by: Vasily Averin <vvs@openvz.org>
> >> Acked-by: Shakeel Butt <shakeelb@google.com>
> >
> > May I ask what information do you want to collect
> > using this patch?
>
> I analyze ftrace output to understand which allocations are accounted.
> When some userspace operation consume memory, it's important to account
> most part of memory (>2/3 of all) to avoid misuse inside memcg-limited
> contianers. Otherwise memcg-limited container can consume significant
> portion of host memory, trigger global OOM, wake up OOM-killer and kill
> random processes on host.
> If memory consumers are accounted, it leads to memcg-OOM only.
>
> Now kmem tracing output looks like this:
>
> kmem_cache_alloc: (getname_flags.part.0+0x2c) call_site=getname_flags.part.0+0x2c ptr=0xffff8fff022e9000 bytes_req=4096 bytes_alloc=4096 gfp_flags=GFP_KERNEL accounted=false
> kmalloc: (alloc_bprm+0x32) call_site=alloc_bprm+0x32 ptr=0xffff8fff2b408a00 bytes_req=416 bytes_alloc=512 gfp_flags=GFP_KERNEL|__GFP_ZERO accounted=false
> kmem_cache_alloc: (mm_alloc+0x16) call_site=mm_alloc+0x16 ptr=0xffff8fff0894d500 bytes_req=1048 bytes_alloc=1088 gfp_flags=GFP_KERNEL accounted=true
> mm_page_alloc: page=0xffffffffa4ab8d42 pfn=0x12ad72 order=1 migratetype=0 gfp_flags=GFP_USER|__GFP_ZERO|__GFP_ACCOUNT
> kmem_cache_alloc: (vm_area_alloc+0x1a) call_site=vm_area_alloc+0x1a ptr=0xffff8fff2af27000 bytes_req=200 bytes_alloc=200 gfp_flags=GFP_KERNEL accounted=true
>
> As you can see, without new field it is quite hard to understand,
> is last allocation accounted.
>
> This analyze helps me to identify most important allocations for given scenario
> and enable accounting for selected allocations.
>
> An example of this analyze you can found here:
> https://lore.kernel.org/all/d28233ee-bccb-7bc3-c2ec-461fd7f95e6a@openvz.org/
>
Thank you for detailed explanation. Makes sense to me.
> > If we decide to do that, it would be better to print
> > something like:
> > slab_flags=SLAB_RECLAIM_ACCOUNT|SLAB_ACCOUNT|SLAB_STORE_USER
> > instead of just printing 'accounted=true/false'. This patch is too
> > specific to SLAB_ACCOUNT.
>
> Any extra output degrades performance.
No strong opinion but just a concern that maybe later someone want add
something similar like 'reclaimable=true/false', 'dma=true/false', ...
and I would prefer more general solution. (especially if we'll not
change tracepoints after release because of backward compatibility)
> For my task it's not important to know SLAB flags, I just need to understand,
> is current allocation accounted or not.
SLAB_ACCOUNT, SLAB_RECLAIM_ACCOUNT, SLAB_DMA, ... etc are SLAB flags.
'if current allocation is accounted or not' depends on SLAB_ACCOUNT
flag is set or not.
Thanks,
Hyeonggon
> > And if what you want to know is just total slab memory that is accounted,
> > what about adding something like SlabAccounted in /proc/meminfo?
>
> It is not enough for me. I need to have per-process allocation information.
>
> Thank you,
> Vasily Averin
next prev parent reply other threads:[~2022-05-22 5:22 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-18 6:24 [PATCH v3] tracing: add 'accounted' entry into output of allocation tracepoints Vasily Averin
2022-05-18 15:09 ` Shakeel Butt
2022-05-18 15:45 ` Vasily Averin
2022-05-18 20:04 ` Steven Rostedt
2022-05-19 11:35 ` Vasily Averin
2022-05-19 14:03 ` Steven Rostedt
2022-05-19 16:29 ` Vasily Averin
2022-05-19 16:32 ` Steven Rostedt
2022-05-21 18:32 ` Vasily Averin
2022-05-21 18:36 ` [PATCH v4] " Vasily Averin
2022-05-22 3:51 ` Hyeonggon Yoo
2022-05-22 4:33 ` Vasily Averin
2022-05-22 5:19 ` Hyeonggon Yoo [this message]
2022-05-22 5:42 ` Shakeel Butt
2022-05-22 18:53 ` Vasily Averin
2022-05-22 20:09 ` Steven Rostedt
2022-05-23 4:03 ` Vasily Averin
2022-05-23 13:12 ` Vlastimil Babka
2022-05-30 7:47 ` [PATCH v5] " Vasily Averin
2022-05-30 8:25 ` Muchun Song
2022-05-31 11:46 ` Hyeonggon Yoo
2022-05-31 16:58 ` Vasily Averin
2022-06-03 3:21 ` [PATCH mm v6] mm/tracing: " Vasily Averin
2022-06-15 9:41 ` Vlastimil Babka
2022-05-25 1:34 ` [PATCH v4] tracing: " Roman Gushchin
2022-05-25 7:33 ` Hyeonggon Yoo
2022-05-25 8:24 ` Vasily Averin
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=YonH2AqfEFYKrUV2@n2.us-central1-a.c.spheric-algebra-350919.internal \
--to=42.hyeyoo@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=cl@linux.com \
--cc=iamjoonsoo.kim@lge.com \
--cc=kernel@openvz.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@suse.com \
--cc=mingo@redhat.com \
--cc=penberg@kernel.org \
--cc=rientjes@google.com \
--cc=roman.gushchin@linux.dev \
--cc=rostedt@goodmis.org \
--cc=shakeelb@google.com \
--cc=songmuchun@bytedance.com \
--cc=vbabka@suse.cz \
--cc=vvs@openvz.org \
--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).