Date: Mon, 8 Oct 2001 13:50:36 -0500 From: Alfred Perlstein <bright@mu.org> To: John Baldwin <jhb@FreeBSD.org> Cc: Bsdguru@aol.com, hackers@freebsd.org Subject: Re: splx() overhead. Message-ID: <20011008135036.L59854@elvis.mu.org> In-Reply-To: <XFMail.011008094521.jhb@FreeBSD.org>; from jhb@FreeBSD.org on Mon, Oct 08, 2001 at 09:45:21AM -0700 References: <16e.20f7124.28f3296e@aol.com> <XFMail.011008094521.jhb@FreeBSD.org>
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* John Baldwin <jhb@FreeBSD.org> [011008 11:46] wrote: > > On 08-Oct-01 Bsdguru@aol.com wrote: > > In doing some kernel profiling analysis it seems that splx is taking up big > > chunks of time. > > That's becaause splx() can result in interrupts blocked during an spl() getting > a chance to run, including soft interrrupts such as softclock and the network > software interrupts. Note that splx itself is quick, it is the releasing of > interrupts which is expensive, which will only happen on the "outside" splx() > if you have nested spl's. It's not the releasing that's expensive, it's _running_ them in the context of the party that does the splx() that makes them look expensive. -- -Alfred Perlstein [alfred@freebsd.org] 'Instead of asking why a piece of software is using "1970s technology," start asking why software is ignoring 30 years of accumulated wisdom.' To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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