From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-vc0-f178.google.com (mail-vc0-f178.google.com [209.85.220.178]) by kanga.kvack.org (Postfix) with ESMTP id 3E5366B0032 for ; Fri, 9 Jan 2015 11:46:01 -0500 (EST) Received: by mail-vc0-f178.google.com with SMTP id hq11so3508502vcb.9 for ; Fri, 09 Jan 2015 08:46:00 -0800 (PST) Received: from mail-vc0-x22a.google.com (mail-vc0-x22a.google.com. [2607:f8b0:400c:c03::22a]) by mx.google.com with ESMTPS id ea10si4275597vdc.73.2015.01.09.08.45.59 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 09 Jan 2015 08:45:59 -0800 (PST) Received: by mail-vc0-f170.google.com with SMTP id hy4so3501049vcb.1 for ; Fri, 09 Jan 2015 08:45:59 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20150108223024.da818218.akpm@linux-foundation.org> References: <20150108223024.da818218.akpm@linux-foundation.org> Date: Fri, 9 Jan 2015 08:45:59 -0800 Message-ID: Subject: Re: mm performance with zram From: Luigi Semenzato Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: linux-mm@kvack.org On Thu, Jan 8, 2015 at 10:30 PM, Andrew Morton wrote: > On Thu, 8 Jan 2015 14:49:45 -0800 Luigi Semenzato wrote: > >> I am taking a closer look at the performance of the Linux MM in the >> context of heavy zram usage. The bottom line is that there is >> surprisingly high overhead (35-40%) from MM code other than >> compression/decompression routines. > > Those images hurt my eyes. Sorry about that. I didn't find other ways of computing the cumulative cost of functions (i.e. time spent in a function and all its descendants, like in gprof). I couldn't get perf to do that either. A flat profile shows most functions take a fracion of 1%, so it's not useful. If anybody knows a better way I'll be glad to use it. > Did you work out where the time is being spent? No, unfortunately it's difficult to make sense of the graph profile as well, especially with my low familiarity with the code. There is a surprising number of different callers into the heaviest nodes and I cannot tell which paths correspond to which high-level actions. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org