Date: Thu, 4 Apr 2013 01:45:36 +0400 From: Gleb Smirnoff <glebius@FreeBSD.org> To: Brooks Davis <brooks@FreeBSD.org> Cc: arch@FreeBSD.org Subject: Re: [CFR][CFT] counter(9): new API for faster and raceless counters Message-ID: <20130403214536.GJ76816@glebius.int.ru> In-Reply-To: <20130403190533.GA97453@lor.one-eyed-alien.net> References: <20130401115128.GZ76816@FreeBSD.org> <20130403190533.GA97453@lor.one-eyed-alien.net>
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On Wed, Apr 03, 2013 at 02:05:33PM -0500, Brooks Davis wrote: B> > o Tiny API for counter(9): B> > B> > counter_u64_t B> > counter_u64_alloc(int wait); B> > B> > void B> > counter_u64_free(counter_u64_t cnt); B> > B> > void B> > counter_u64_add(counter_u64_t cnt, uint64_t inc); B> > B> > uint64_t B> > counter_u64_fetch(counter_u64_t cnt); B> B> I wonder if there might be value in an interface to retrieve the per-cpu B> values individually. The use case I have in mind is interrupt counters B> on our BERI CPU. Similar to the Sibyte MIPS SoCs, our PIC always routes B> each interrupt to a specific hardware thread. I'd ideally like to be able B> to look at at hardware interrupts on a per-thread basis and avoid the B> cache trashing behavior we'd get if we allocated current interrupt B> counters to each one, but we probably want to be able to preserve B> something like the current behavior. You can just utilize directly the per-CPU UMA zones, that will come together with counter(9). So, the code will look like: critical_enter(); foo = (foo *)zpcpu_get(base); /* get private to CPU data */ do smth with foo critical_exit(); -- Totus tuus, Glebius.
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