From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758055Ab0IURAi (ORCPT ); Tue, 21 Sep 2010 13:00:38 -0400 Received: from mail-fx0-f46.google.com ([209.85.161.46]:56392 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757861Ab0IURAg (ORCPT ); Tue, 21 Sep 2010 13:00:36 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=subject:from:to:cc:in-reply-to:references:content-type:date :message-id:mime-version:x-mailer:content-transfer-encoding; b=sMpECBg+LGn4AHb+N1xIbRVmsIJFUuq3ewvZanN+5FdCcDlB293NXrlAt3d/eqwdKo TE3CGENklS53b7Dw91L3NnZJ3MPfjqxQqnzZv+zxhL2cKtUwf+b/p11f1O/gX9DWgcOQ q8KFyRUvo6yTAnyKQy8+T44600DQHS/tKAnG0= Subject: Re: [PATCH] mm: do not print backtraces on GFP_ATOMIC failures From: Eric Dumazet To: Andrew Morton Cc: Rik van Riel , linux-mm@kvack.org, linux-kernel@vger.kernel.org, KOSAKI Motohiro , netdev@vger.kernel.org In-Reply-To: <20100921094638.9910add0.akpm@linux-foundation.org> References: <20100921121818.4745f038@annuminas.surriel.com> <20100921094638.9910add0.akpm@linux-foundation.org> Content-Type: text/plain; charset="UTF-8" Date: Tue, 21 Sep 2010 19:00:27 +0200 Message-ID: <1285088427.2617.723.camel@edumazet-laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le mardi 21 septembre 2010 à 09:46 -0700, Andrew Morton a écrit : > On Tue, 21 Sep 2010 12:18:18 -0400 Rik van Riel wrote: > > > Atomic allocations cannot fall back to the page eviction code > > and are expected to fail. In fact, in some network intensive > > workloads, it is common to experience hundreds of GFP_ATOMIC > > allocation failures. > > > > Printing out a backtrace for every one of those expected > > allocation failures accomplishes nothing good. At multi-gigabit > > network speeds with jumbo frames, a burst of allocation failure > > backtraces could even slow down the system. > > > > We're better off not printing out backtraces on GFP_ATOMIC > > allocation failures. > > > > Signed-off-by: Rik van Riel > > > > diff --git a/include/linux/gfp.h b/include/linux/gfp.h > > index 975609c..5a0bddb 100644 > > --- a/include/linux/gfp.h > > +++ b/include/linux/gfp.h > > @@ -72,7 +72,7 @@ struct vm_area_struct; > > /* This equals 0, but use constants in case they ever change */ > > #define GFP_NOWAIT (GFP_ATOMIC & ~__GFP_HIGH) > > /* GFP_ATOMIC means both !wait (__GFP_WAIT not set) and use emergency pool */ > > -#define GFP_ATOMIC (__GFP_HIGH) > > +#define GFP_ATOMIC (__GFP_HIGH | __GFP_NOWARN) > > #define GFP_NOIO (__GFP_WAIT) > > #define GFP_NOFS (__GFP_WAIT | __GFP_IO) > > #define GFP_KERNEL (__GFP_WAIT | __GFP_IO | __GFP_FS) > > A much finer-tuned implementation would be to add __GFP_NOWARN just to > the networking call sites. I asked about this in June and it got > nixed: > > http://www.spinics.net/lists/netdev/msg131965.html > -- Yes, I remember this particular report was useful to find and correct a bug. I dont know what to say. Being silent or verbose, it really depends on the context ?