From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx148.postini.com [74.125.245.148]) by kanga.kvack.org (Postfix) with SMTP id 72B0D6B00D8 for ; Wed, 29 May 2013 15:26:07 -0400 (EDT) Date: Wed, 29 May 2013 12:26:05 -0700 From: Andrew Morton Subject: Re: [PATCH v2 1/2] Make the batch size of the percpu_counter configurable Message-Id: <20130529122605.082cbb1ad8f5cbc9e82e7b16@linux-foundation.org> In-Reply-To: <1369265838.27102.351.camel@schen9-DESK> References: <8584b08e57e97ecc4769859b751ad459d038a730.1367574872.git.tim.c.chen@linux.intel.com> <20130521134122.4d8ea920c0f851fc2d97abc9@linux-foundation.org> <1369178849.27102.330.camel@schen9-DESK> <20130521164154.bed705c6e117ceb76205cd65@linux-foundation.org> <1369183390.27102.337.camel@schen9-DESK> <20130522002020.60c3808f.akpm@linux-foundation.org> <1369265838.27102.351.camel@schen9-DESK> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Tim Chen Cc: Tejun Heo , Christoph Lameter , Al Viro , Eric Dumazet , Ric Mason , Simon Jeons , Dave Hansen , Andi Kleen , linux-kernel , linux-mm On Wed, 22 May 2013 16:37:18 -0700 Tim Chen wrote: > Currently the per cpu counter's batch size for memory accounting is > configured as twice the number of cpus in the system. However, > for system with very large memory, it is more appropriate to make it > proportional to the memory size per cpu in the system. > > For example, for a x86_64 system with 64 cpus and 128 GB of memory, > the batch size is only 2*64 pages (0.5 MB). So any memory accounting > changes of more than 0.5MB will overflow the per cpu counter into > the global counter. Instead, for the new scheme, the batch size > is configured to be 0.4% of the memory/cpu = 8MB (128 GB/64 /256), > which is more inline with the memory size. I renamed the patch to "mm: tune vm_committed_as percpu_counter batching size". Do we have any performance testing results? They're pretty important for a performance-improvement patch ;) -- 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