From owner-freebsd-hackers Mon Oct 8 11:50:46 2001 Delivered-To: freebsd-hackers@freebsd.org Received: from elvis.mu.org (elvis.mu.org [216.33.66.196]) by hub.freebsd.org (Postfix) with ESMTP id 9339C37B40C; Mon, 8 Oct 2001 11:50:41 -0700 (PDT) Received: by elvis.mu.org (Postfix, from userid 1192) id 75F8881D08; Mon, 8 Oct 2001 13:50:36 -0500 (CDT) Date: Mon, 8 Oct 2001 13:50:36 -0500 From: Alfred Perlstein To: John Baldwin Cc: Bsdguru@aol.com, hackers@freebsd.org Subject: Re: splx() overhead. Message-ID: <20011008135036.L59854@elvis.mu.org> References: <16e.20f7124.28f3296e@aol.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: ; from jhb@FreeBSD.org on Mon, Oct 08, 2001 at 09:45:21AM -0700 Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG * John Baldwin [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