Re: [PATCH] mm: don't warn about allocations which stall for too long

From: peter enderborg <peter.enderborg@sony.com>
To: Michal Hocko <mhocko@kernel.org>,
	peter enderborg <peter.enderborg@sonymobile.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	akpm@linux-foundation.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org,
	Cong Wang <xiyou.wangcong@gmail.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Mel Gorman <mgorman@suse.de>, Petr Mladek <pmladek@suse.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	"yuwang.yuwang" <yuwang.yuwang@alibaba-inc.com>
Subject: Re: [PATCH] mm: don't warn about allocations which stall for too long
Date: Thu, 9 Nov 2017 10:34:46 +0100	[thread overview]
Message-ID: <ef81333e-0e19-c6f6-a960-093dc60fb75c@sony.com> (raw)
In-Reply-To: <20171109085249.guihvx5tzm77u3qk@dhcp22.suse.cz>

On 11/09/2017 09:52 AM, Michal Hocko wrote:
> I am not sure. I would rather see a tracepoint to mark the allocator
> entry. This would allow both 1) measuring the allocation latency (to
> compare it to the trace_mm_page_alloc and 2) check for stalls with
> arbitrary user defined timeout (just print all allocations which haven't
> passed trace_mm_page_alloc for the given amount of time).

Traces are not that expensive, but there are more than few in calls in this path. And Im trying to
keep it as small that it can used for maintenance versions too.

This is suggestion is a quick way of keeping the current solution for the ones that are interested
the slow allocations. If we are going for a solution with a time-out parameter from the user what
interface do you suggest to do this configuration. A filter parameter for the event?

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