Date: Thu, 6 Apr 2006 13:11:29 -0400 From: John Baldwin <jhb@freebsd.org> To: Julian Elischer <julian@elischer.org> Cc: Luigi Rizzo <rizzo@icir.org>, freebsd-current@freebsd.org Subject: Re: Interesting data on network interrupt - part II Message-ID: <200604061311.31632.jhb@freebsd.org> In-Reply-To: <4434394F.8020105@elischer.org> References: <20060405003358.GA83600@tin.it> <200604051638.59800.jhb@freebsd.org> <4434394F.8020105@elischer.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On Wednesday 05 April 2006 17:40, Julian Elischer wrote: > John Baldwin wrote: > > >On Tuesday 04 April 2006 20:33, Paolo Pisati wrote: > > > > > >>Hi, > >> > >>i updated my work on interrupt profiling with sone new > >>experiments. > >> > >>In total we have now: > >> > >>-FreeBSD 4 PIC (no asm part) > >>-FreeBSD 7 APIC > >>-FreeBSD 7 PIC > >>-FreeBSD 7 PREE APIC > >>-FreeBSD 7 APIC JHB > >> > >>Some quick comments: > >> > >>-PIC is much slower in masking interrupt (7k in PIC vs 3k in APIC) > >>-PREE let new thread save less than 500 ticks of 'queue' while > >> preempted threads are often resumed after a lot > >>-JHB patch shaved 2.5k ticks in interrupt masking op > >> > >>For graphs, data and more comments: > >> > >>http://mercurio.sm.dsi.unimi.it/~pisati/interrupt/ > >> > >> > > > >I'll commit the patch then. :) One thing you might try to do to better > >measure the effects of preemption is to generate kernel work so that > >the bge interrupts occur while the current thread is in the kernel > >rather than in userland. In that case preemption should provide much > >lower latency for interrupt handlers, as w/o preemption, an interrupt > >in kernel mode won't run the ithread until either curthread blocks or > >returns to userland. > > > > > > it looks a bit like the preempted threads shuld be put onto a stack of > threads to resume > so that when the pre-empter finishes, teh previosly active thread is > resumed. > Basically, a preempted thread should be put at the HEAD of it's run > queue, and not the tail.. You changed the scheduler to already do that. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200604061311.31632.jhb>