From: Joel Fernandes <joelaf@google.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Zhaoyang Huang <huangzhaoyang@gmail.com>,
Ingo Molnar <mingo@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
kernel-patch-test@lists.linaro.org,
Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@suse.com>,
"open list:MEMORY MANAGEMENT" <linux-mm@kvack.org>,
Vlastimil Babka <vbabka@suse.cz>,
Michal Hocko <mhocko@kernel.org>
Subject: Re: [PATCH v1] kernel/trace:check the val against the available mem
Date: Fri, 30 Mar 2018 13:37:24 -0700 [thread overview]
Message-ID: <CAJWu+ooihz7KJG6Av2THBda2mUd=u-zsNVeB4V7XrQNSwxaHNA@mail.gmail.com> (raw)
In-Reply-To: <20180330151037.30d2ac6d@gandalf.local.home>
Hi Steve,
On Fri, Mar 30, 2018 at 12:10 PM, Steven Rostedt <rostedt@goodmis.org> wrote:
[..]
>> > I wonder if I should have the ring buffer allocate groups of pages, to
>> > avoid this. Or try to allocate with NORETRY, one page at a time, and
>> > when that fails, allocate groups of pages with RETRY_MAYFAIL, and that
>> > may keep it from causing an OOM?
>> >
>>
>> I don't see immediately how that can prevent an OOM in other
>> applications here? If ftrace allocates lots of memory with
>> RETRY_MAYFAIL, then we would still OOM in other applications if memory
>> isn't available. Sorry if I missed something.
>
> Here's the idea.
>
> Allocate one page at a time with NORETRY. If that fails, then allocate
> larger amounts (higher order of pages) with RETRY_MAYFAIL. Then if it
> can't get all the memory it needs, it wont take up all memory in the
> system before it finds out that it can't have any more.
>
> Or perhaps the memory management system can provide a
> get_available_mem() function that ftrace could call before it tries to
> increase the ring buffer and take up all the memory of the system
> before it realizes that it can't get all the memory it wants.
>
> The main problem I have with Zhaoyang's patch is that
> get_available_mem() does not belong in the tracing code. It should be
> something that the mm subsystem provides.
>
Cool. Personally I like the getting of available memory solution and
use that, since its simpler.
MM already provides it through si_mem_available since the commit
"mm/page_alloc.c: calculate 'available' memory in a separate function"
(sha d02bd27b). Maybe we could just use that?
MemAvailable was initially added in commit "/proc/meminfo: provide
estimated available memory" (sha 34e431b0ae39)
thanks,
- Joel
next prev parent reply other threads:[~2018-03-30 20:37 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-29 10:41 [PATCH v1] kernel/trace:check the val against the available mem Zhaoyang Huang
2018-03-29 16:05 ` Steven Rostedt
2018-03-30 3:32 ` Zhaoyang Huang
2018-03-30 14:07 ` Steven Rostedt
2018-03-30 6:53 ` [Kernel-patch-test] " kbuild test robot
2018-03-30 6:54 ` kbuild test robot
2018-03-30 14:20 ` Steven Rostedt
2018-03-30 16:37 ` Joel Fernandes
2018-03-30 19:10 ` Steven Rostedt
2018-03-30 20:37 ` Joel Fernandes [this message]
2018-03-30 20:53 ` Matthew Wilcox
2018-03-30 21:30 ` Steven Rostedt
2018-03-30 21:42 ` Steven Rostedt
2018-03-30 23:38 ` Joel Fernandes
2018-03-31 1:41 ` Steven Rostedt
2018-03-31 2:18 ` Matthew Wilcox
2018-03-31 3:07 ` Steven Rostedt
2018-03-31 5:44 ` Joel Fernandes
2018-04-02 0:52 ` Zhaoyang Huang
2018-04-03 11:06 ` Michal Hocko
2018-04-03 11:51 ` Steven Rostedt
2018-04-03 12:16 ` Michal Hocko
2018-04-03 12:23 ` Steven Rostedt
2018-04-03 12:35 ` Michal Hocko
2018-04-03 13:32 ` Steven Rostedt
2018-04-03 13:56 ` Michal Hocko
2018-04-03 14:17 ` Steven Rostedt
2018-04-03 16:11 ` Michal Hocko
2018-04-03 16:59 ` Steven Rostedt
2018-04-03 22:56 ` Steven Rostedt
2018-04-04 6:20 ` Michal Hocko
2018-04-04 12:21 ` Joel Fernandes
2018-04-04 12:59 ` Steven Rostedt
2018-04-04 14:10 ` Michal Hocko
2018-04-04 14:25 ` Steven Rostedt
2018-04-04 14:42 ` Michal Hocko
2018-04-04 15:04 ` Steven Rostedt
2018-04-04 15:27 ` Michal Hocko
2018-04-04 15:38 ` Steven Rostedt
2018-04-04 2:58 ` Zhaoyang Huang
2018-04-04 6:23 ` Michal Hocko
2018-04-04 9:29 ` Zhaoyang Huang
2018-04-04 14:11 ` Steven Rostedt
2018-04-04 14:23 ` Michal Hocko
2018-04-04 14:31 ` Steven Rostedt
2018-04-04 14:47 ` Michal Hocko
2018-04-04 15:47 ` Steven Rostedt
2018-04-05 2:58 ` Matthew Wilcox
2018-04-05 4:12 ` Joel Fernandes
2018-04-05 14:22 ` Matthew Wilcox
2018-04-05 14:27 ` Michal Hocko
2018-04-05 14:34 ` Steven Rostedt
2018-04-05 15:13 ` Matthew Wilcox
2018-04-05 15:32 ` Michal Hocko
2018-04-05 16:15 ` Matthew Wilcox
2018-04-05 18:54 ` Michal Hocko
2018-04-05 20:15 ` __GFP_LOW Matthew Wilcox
2018-04-06 6:09 ` __GFP_LOW Michal Hocko
2018-04-08 4:27 ` __GFP_LOW Matthew Wilcox
2018-04-09 7:34 ` __GFP_LOW Michal Hocko
2018-04-09 15:51 ` __GFP_LOW Matthew Wilcox
2018-04-09 18:14 ` __GFP_LOW Michal Hocko
[not found] ` <CA+JonM0HG9kWb6-0iyDQ8UMxTeR-f=+ZL89t5DvvDULDC8Sfyw@mail.gmail.com>
2018-04-10 12:19 ` __GFP_LOW Matthew Wilcox
2018-04-05 14:30 ` [PATCH v1] kernel/trace:check the val against the available mem Steven Rostedt
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