From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx170.postini.com [74.125.245.170]) by kanga.kvack.org (Postfix) with SMTP id D6AFF6B012B for ; Tue, 30 Apr 2013 13:28:35 -0400 (EDT) Date: Tue, 30 Apr 2013 17:28:34 +0000 From: Christoph Lameter Subject: Re: [PATCH 1/2] Make the batch size of the percpu_counter configurable In-Reply-To: <1367339009.27102.174.camel@schen9-DESK> Message-ID: <0000013e5bfd1548-a6ef7962-7b00-495b-8e83-d7a08413e165-000000@email.amazonses.com> References: <0000013e5b24d2c5-9b899862-e2fd-4413-8094-4f1e5a0c0f62-000000@email.amazonses.com> <1367339009.27102.174.camel@schen9-DESK> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Tim Chen Cc: Andrew Morton , Tejun Heo , Al Viro , Dave Hansen , Andi Kleen , linux-kernel , linux-mm On Tue, 30 Apr 2013, Tim Chen wrote: > On Tue, 2013-04-30 at 13:32 +0000, Christoph Lameter wrote: > > On Mon, 29 Apr 2013, Tim Chen wrote: > > > > > diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h > > > index d5dd465..5ca7df5 100644 > > > --- a/include/linux/percpu_counter.h > > > +++ b/include/linux/percpu_counter.h > > > @@ -22,6 +22,7 @@ struct percpu_counter { > > > struct list_head list; /* All percpu_counters are on a list */ > > > #endif > > > s32 __percpu *counters; > > > + int *batch ____cacheline_aligned_in_smp; > > > }; > > > > What is this for and why does it have that alignmend? > > I was assuming that if batch is frequently referenced, it probably > should not share a cache line with the counters field. And why is it a pointer? And the pointer is so frequently changed that it needs it own cache line? -- 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