Path: csiph.com!feeder.erje.net!2.eu.feeder.erje.net!fu-berlin.de!bofh.it!news.nic.it!robomod From: Michal Hocko Newsgroups: linux.kernel Subject: Re: [PATCH] mm: throttle show_mem from warn_alloc Date: Tue, 20 Dec 2016 09:40:02 +0100 Message-ID: References: X-Original-To: Andrew Morton X-Google-Dkim-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=gBnk6mI7to3CuxiMK+DU9kWcRPfM+h/Iy1535tW7N1A=; b=V4shp6KQcTsloWtbiAxtMEHWwoqd2yngPll5RfJ/cPlbgohwHVse2YlNNjPDRAVuqX evS1bhQ7qePs9lJgpe8+msqnheKBU2WToYOMJbqxGulS29cpn1DMDYGNndlyFbf7VgM/ IQAtBgtuIR5shg4Tyog025i62UE2/N2c8LNhzYF8vb/jlfrvi6YMWgVAw70fJ34q8gmq 7WqMtiNzk2hVVfBczUrNiqSEGj94HbdtucrDK7rWeg1hzHKLhG2di4+ZC4CbyA4rZne7 IT2ts7Sf2+nXPnXz1Z5Rp1dnDrq12yDL6CMgd3+V9imXHfdGjI/MxElDF8cXS2OrA6Gi NPXQ== X-Gm-Message-State: AIkVDXJQykhMcQ3/3UBsSOPFdAJ8MqS8ofpQjgr2AMGy3fxSHPluUMrNac4cLoAuzm04/g== X-Received: by 10.28.142.5 with SMTP id q5mr804024wmd.78.1482222939499; Tue, 20 Dec 2016 00:35:39 -0800 (PST) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.6.0 (2016-04-01) Sender: robomod@news.nic.it List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Approved: robomod@news.nic.it Lines: 61 Organization: linux.* mail to news gateway X-Original-Cc: Tetsuo Handa , linux-mm@kvack.org, LKML X-Original-Date: Tue, 20 Dec 2016 09:35:38 +0100 X-Original-Message-ID: <20161220083537.GA3769@dhcp22.suse.cz> X-Original-References: <20161215101510.9030-1-mhocko@kernel.org> <20161219152125.f77ddf79f3c89e5cdd0e02d6@linux-foundation.org> X-Original-Sender: linux-kernel-owner@vger.kernel.org Xref: csiph.com linux.kernel:1544984 On Mon 19-12-16 15:21:25, Andrew Morton wrote: > On Thu, 15 Dec 2016 11:15:10 +0100 Michal Hocko wrote: > > > Tetsuo has been stressing OOM killer path with many parallel allocation > > requests when he has noticed that it is not all that hard to swamp > > kernel logs with warn_alloc messages caused by allocation stalls. Even > > though the allocation stall message is triggered only once in 10s there > > might be many different tasks hitting it roughly around the same time. > > > > A big part of the output is show_mem() which can generate a lot of > > output even on a small machines. There is no reason to show the state of > > memory counter for each allocation stall, especially when multiple of > > them are reported in a short time period. Chances are that not much has > > changed since the last report. This patch simply rate limits show_mem > > called from warn_alloc to only dump something once per second. This > > should be enough to give us a clue why an allocation might be stalling > > while burst of warnings will not swamp log with too much data. > > > > While we are at it, extract all the show_mem related handling (filters) > > into a separate function warn_alloc_show_mem. This will make the code > > cleaner and as a bonus point we can distinguish which part of warn_alloc > > got throttled due to rate limiting as ___ratelimit dumps the caller. > > These guys don't need file-wide scope... > > --- a/mm/page_alloc.c~mm-throttle-show_mem-from-warn_alloc-fix > +++ a/mm/page_alloc.c > @@ -3018,15 +3018,10 @@ static inline bool should_suppress_show_ > return ret; > } > > -static DEFINE_RATELIMIT_STATE(nopage_rs, > - DEFAULT_RATELIMIT_INTERVAL, > - DEFAULT_RATELIMIT_BURST); > - > -static DEFINE_RATELIMIT_STATE(show_mem_rs, HZ, 1); > - > static void warn_alloc_show_mem(gfp_t gfp_mask) > { > unsigned int filter = SHOW_MEM_FILTER_NODES; > + static DEFINE_RATELIMIT_STATE(show_mem_rs, HZ, 1); > > if (should_suppress_show_mem() || !__ratelimit(&show_mem_rs)) > return; > @@ -3050,6 +3045,8 @@ void warn_alloc(gfp_t gfp_mask, const ch > { > struct va_format vaf; > va_list args; > + static DEFINE_RATELIMIT_STATE(nopage_rs, DEFAULT_RATELIMIT_INTERVAL, > + DEFAULT_RATELIMIT_BURST); > > if ((gfp_mask & __GFP_NOWARN) || !__ratelimit(&nopage_rs) || > debug_guardpage_minorder() > 0) > _ > Acked-by: Michal Hocko -- Michal Hocko SUSE Labs