Date: Wed, 26 Jun 2013 13:12:11 +0400 (MSK) From: Dmitry Morozovsky <marck@rinet.ru> To: Konstantin Belousov <kostikbel@gmail.com> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, Gleb Smirnoff <glebius@freebsd.org>, src-committers@freebsd.org, Bruce Evans <brde@optusnet.com.au> Subject: Re: svn commit: r252032 - head/sys/amd64/include Message-ID: <alpine.BSF.2.00.1306261311060.1846@woozle.rinet.ru> In-Reply-To: <20130625205826.GM91021@kib.kiev.ua> References: <20130621135427.GA1214@FreeBSD.org> <20130622110352.J2033@besplex.bde.org> <20130622124832.S2347@besplex.bde.org> <20130622174921.I3112@besplex.bde.org> <20130623073343.GY91021@kib.kiev.ua> <20130623181458.J2256@besplex.bde.org> <20130624170849.GH91021@kib.kiev.ua> <20130625102023.K899@besplex.bde.org> <20130625062039.GJ91021@kib.kiev.ua> <20130625190352.P986@besplex.bde.org> <20130625205826.GM91021@kib.kiev.ua>
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On Tue, 25 Jun 2013, Konstantin Belousov wrote: > > > Updates to the counter cannot be done from the interrupt context. > > > > This is fragile, however. It prevents using counters for things like > > counting interrupts. Most interrupt counting is now done directlyly > > and doesn't use PCPU_INC(). i386/i386 has just 1 use of PCPU_INC(). > > It is to count traps in machdep.c. Traps include nonmaskable > > interrupts. Even hard-disabling of interrupts doesn't prevent these. > > Otherwise, PCPU is used mainly for vm counters. E.g., for pagefaults. > > Now the trap is not an interrupt, so it shouldn't occur in the middle > > of the counter update and the PCPU_INC() can safely be replaced by > > a counter, but this is not clear. > Traps are not performance critical in the sense that there is no need to count > up to 1-10G traps per second. Anyway, as Gleb said, there is no point in > optimizing the i386 kernel. Hmm, don't we count semi-embedded routers? Or, do we think they are either amd64 or arm/mips? [snip all the rest] -- Sincerely, D.Marck [DM5020, MCK-RIPE, DM3-RIPN] [ FreeBSD committer: marck@FreeBSD.org ] ------------------------------------------------------------------------ *** Dmitry Morozovsky --- D.Marck --- Wild Woozle --- marck@rinet.ru *** ------------------------------------------------------------------------
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