Date: Wed, 04 May 2011 15:18:35 +0200 From: Alexander Leidinger <Alexander@Leidinger.net> To: lev@FreeBSD.org Cc: freebsd-stable@FreeBSD.org Subject: Re: How to understand, what userland program does in kernel? Message-ID: <20110504151835.10858df55klyghf4@webmail.leidinger.net> In-Reply-To: <455293202.20110504164901@serebryakov.spb.ru> References: <455293202.20110504164901@serebryakov.spb.ru>
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Quoting Lev Serebryakov <lev@FreeBSD.org> (from Wed, 4 May 2011 16:49:01 +0400): > Hello, Freebsd-stable. > > I have userland program (transmission BT client), which spent 100% > of one core of E4500 CPU when it has many peers. It is surprises me, > as channel is only 35Mbit, and my "Linux" friends can upload much more > on comparable hardware. > > But what surprises me even more, that 50% of this time it spends as > System time. > > Is here any way to understand, what transmission does in kernel for > so much time? It seems, that userland profiling doesn't help me, am I > right? ktrace and dtrace are your friends. ktrace for a simple "it makes those syscalls/ioctls/..." type of information gathering, and dtrace for in-deep investigation. Bye, Alexander. -- The difference between a good haircut and a bad one is seven days. http://www.Leidinger.net Alexander @ Leidinger.net: PGP ID = B0063FE7 http://www.FreeBSD.org netchild @ FreeBSD.org : PGP ID = 72077137
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