Date: Tue, 16 Jan 2007 14:19:04 -0700 From: Scott Long <scottl@samsco.org> To: John Baldwin <jhb@freebsd.org> Cc: Pawel Jakub Dawidek <pjd@freebsd.org>, Kip Macy <kip.macy@gmail.com>, Suleiman Souhlal <ssouhlal@freebsd.org>, Attilio Rao <attilio@freebsd.org>, freebsd-current@freebsd.org, freebsd-arch@freebsd.org Subject: Re: [PATCH] Mantaining turnstile aligned to 128 bytes in i386 CPUs Message-ID: <45AD4148.90002@samsco.org> In-Reply-To: <200701161605.22394.jhb@freebsd.org> References: <3bbf2fe10607250813w8ff9e34pc505bf290e71758@mail.gmail.com> <200701161438.52481.jhb@freebsd.org> <3bbf2fe10701161236s48e6cc16p99c8c38c1d7becde@mail.gmail.com> <200701161605.22394.jhb@freebsd.org>
next in thread | previous in thread | raw e-mail | index | archive | help
John Baldwin wrote: > 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? > If you always cache-line-align them, that also addresses the Intel recommendation to always keep them from sharing cache lines. Scott
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?45AD4148.90002>