Date: Tue, 16 Jan 2007 16:05:21 -0500 From: John Baldwin <jhb@freebsd.org> To: "Attilio Rao" <attilio@freebsd.org> Cc: Kip Macy <kip.macy@gmail.com>, freebsd-current@freebsd.org, Suleiman Souhlal <ssouhlal@freebsd.org>, Pawel Jakub Dawidek <pjd@freebsd.org>, freebsd-arch@freebsd.org Subject: Re: [PATCH] Mantaining turnstile aligned to 128 bytes in i386 CPUs Message-ID: <200701161605.22394.jhb@freebsd.org> In-Reply-To: <3bbf2fe10701161236s48e6cc16p99c8c38c1d7becde@mail.gmail.com> References: <3bbf2fe10607250813w8ff9e34pc505bf290e71758@mail.gmail.com> <200701161438.52481.jhb@freebsd.org> <3bbf2fe10701161236s48e6cc16p99c8c38c1d7becde@mail.gmail.com>
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On Tuesday 16 January 2007 15:36, Attilio Rao wrote: > 2007/1/16, John Baldwin <jhb@freebsd.org>: > > On Tuesday 16 January 2007 11:51, Attilio Rao wrote: > > > 2006/7/28, Attilio Rao <attilio@freebsd.org>: > > > > > > > > After some thinking, I think it's better using init/fini methods > > > > (since they hide the sizeof(struct turnstile) with size parameter). > > > > > > > > Feedbacks and comments are welcome: > > > > http://users.gufi.org/~rookie/works/patches/uma_sync_init.diff > > > > > > [CC'ed all the interested people] > > > > > > Even if a long time is passed I did some benchmarks based on ebizzy tool. > > > This program claims to reproduce a real httpd server behaviour and is > > > used into the Linux world for benchmarks, AFAIK. > > > I think that results of the comparison on this patch is very > > > interesting, and I think it worths a commit :) > > > I think that results can be even better on a Xeon machine (I had no > > > chance to reproduce this on some of these). > > > (Results taken in consideration have been measured after some starts, > > > in order to minimize caching differences). > > > > > > The patch: > > > http://users.gufi.org/~rookie/works/patches/ts-sq/ts-sq.diff > > > > Looks good. Some minor nits are that in subr_turnstile.c in the comment I > > would say "a turnstile is allocated" rather than "a turnstile is got from a > > specific UMA zone" as it reads a little bit clearer. Also, I would > > say "Allocate a" rather than "Get a" for the two _alloc() functions. Also, > > why not just use UMA_ALIGN_CACHE and make UMA_ALIGN_CACHE (128 - 1) on i386 > > and amd64 rather than adding a new UMA_ALIGN_SYNC? > > I was thinking that in this way anyone who wants to replace the > syncronizing primitive boundary to an appropriate value can do it. > I just used UMA_ALIGN_CACHE as default value beacause I don't know the > better boundary (for syncronizing primitives) for other arches. Is there a good reason to not cache-align synch primitives? That is, why would an arch not use cache-align? Also, is there a reason to not update UMA_ALIGN_CACHE on x86? -- John Baldwin
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