Date: Mon, 5 Nov 2012 13:12:57 -0500 From: Eitan Adler <lists@eitanadler.com> To: Ian Lepore <freebsd@damnhippie.dyndns.org> Cc: "Rodney W. Grimes" <freebsd@pdx.rh.cn85.chatusa.com>, Juli Mallett <juli@clockworksquid.com>, "freebsd-mips@FreeBSD.org" <freebsd-mips@freebsd.org> Subject: Re: CACHE_LINE_SIZE macro. Message-ID: <CAF6rxgnMwiAr4FSaHF0sEGFCJ7Lh-Su5n3x2jNriNb-YPFrvjA@mail.gmail.com> In-Reply-To: <1352138944.1120.187.camel@revolution.hippie.lan> References: <CACVs6=_BrwJ19CPj7OqKvV8boHfujVWqn96u3VPUmZ040JpAeQ@mail.gmail.com> <201211041828.qA4ISomC076058@pdx.rh.CN85.ChatUSA.com> <CAF6rxgn-bNJOuvdiRj_UUGQUTRaeOt54OdzHOioNz5f566hoig@mail.gmail.com> <DAE462F0-9D85-4942-8826-C0709E36D3B7@bsdimp.com> <CAF6rxg=Et1d6u4RBCB88KibW_uiaRbNdb75v0TQOr-0BrEXV=g@mail.gmail.com> <B4225C25-BD43-423C-A1A2-C9FD4AC92ECB@bsdimp.com> <1352137087.1120.180.camel@revolution.hippie.lan> <E68E4C16-64E5-460E-B13C-164FDA89436C@bsdimp.com> <1352138944.1120.187.camel@revolution.hippie.lan>
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On 5 November 2012 13:09, Ian Lepore <freebsd@damnhippie.dyndns.org> wrote: > The other thing that bugs me is that cache is a scarce resource on our > wimpy little platforms, and padding just ensures that we use it even > less effectively in the UP case. It seems like it's more likely to kill > performance than improve it, because one would expect that when a lock > is embedded in a structure, there's going to be access to other data > nearby once the lock is acquired. This is another reason to encourage the separation between the real cache line size and the lock padding version. On low cache-size environments the latter could be tuned to not matter. -- Eitan Adler
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