Date: Mon, 8 Apr 2013 23:44:36 +0400 From: Gleb Smirnoff <glebius@FreeBSD.org> To: John Baldwin <jhb@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r249265 - in head/sys: amd64/include arm/include i386/include ia64/include mips/include powerpc/include sparc64/include sys Message-ID: <20130408194436.GI76816@FreeBSD.org> In-Reply-To: <201304081541.27408.jhb@freebsd.org> References: <201304081919.r38JJAvB088644@svn.freebsd.org> <201304081541.27408.jhb@freebsd.org>
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On Mon, Apr 08, 2013 at 03:41:27PM -0400, John Baldwin wrote: J> On Monday, April 08, 2013 3:19:10 pm Gleb Smirnoff wrote: J> > Author: glebius J> > Date: Mon Apr 8 19:19:10 2013 J> > New Revision: 249265 J> > URL: http://svnweb.freebsd.org/changeset/base/249265 J> > J> > Log: J> > Merge from projects/counters: J> > J> > Pad struct pcpu so that its size is denominator of PAGE_SIZE. This J> > is done to reduce memory waste in UMA_PCPU_ZONE zones. J> > J> > Sponsored by: Nginx, Inc. J> > J> > Modified: head/sys/sys/pcpu.h J> > J> ============================================================================== J> > --- head/sys/sys/pcpu.h Mon Apr 8 19:10:45 2013 (r249264) J> > +++ head/sys/sys/pcpu.h Mon Apr 8 19:19:10 2013 (r249265) J> > @@ -180,6 +180,14 @@ struct pcpu { J> > PCPU_MD_FIELDS; J> > } __aligned(CACHE_LINE_SIZE); J> J> Why not change this to be PAGE_SIZE rather than putting explicit padding in J> all the pcpu fields? That would seem to be more maintainable. Because it can be smaller than PAGE_SIZE. Two times smaller, four times smaller. -- Totus tuus, Glebius.
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