Date: Thu, 15 Jan 2015 19:48:00 +0300 From: Slawa Olhovchenkov <slw@zxy.spb.ru> To: Hans Petter Selasky <hps@selasky.org> Cc: Adrian Chadd <adrian@freebsd.org>, FreeBSD Current <freebsd-current@freebsd.org>, sbruno@freebsd.org, Jason Wolfe <nitroboost@gmail.com>, "freebsd-arch@freebsd.org" <freebsd-arch@freebsd.org> Subject: Re: [RFC] kern/kern_timeout.c rewrite in progress Message-ID: <20150115164800.GF3698@zxy.spb.ru> In-Reply-To: <54B7EDFC.9020406@selasky.org> References: <54A9A71E.70609@selasky.org> <CAAAm0r39Sv3TCvwaCiNQ1Y9iBVtY_nb0A_iNOC41bgxqXmt%2B4w@mail.gmail.com> <54B29A49.3080600@selasky.org> <CAAAm0r2eNYicq%2BKKj5f5EE%2BKLPxdvy15wj1ZWS=zA6sgOtcoGQ@mail.gmail.com> <54B67DA7.3070106@selasky.org> <54B7DECF.8070209@selasky.org> <20150115154617.GB10325@zxy.spb.ru> <54B7E1E4.6040906@selasky.org> <20150115155810.GE3698@zxy.spb.ru> <54B7EDFC.9020406@selasky.org>
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On Thu, Jan 15, 2015 at 05:42:36PM +0100, Hans Petter Selasky wrote: > On 01/15/15 16:58, Slawa Olhovchenkov wrote: > > On Thu, Jan 15, 2015 at 04:51:00PM +0100, Hans Petter Selasky wrote: > > > >> On 01/15/15 16:46, Slawa Olhovchenkov wrote: > >>> On Thu, Jan 15, 2015 at 04:37:51PM +0100, Hans Petter Selasky wrote: > >>> > >>> Only stability impovement? > >>> Or performance too? > >> > >> Hi, > >> > >> Stability improvement mostly. Should not affect performance from what I > >> know. Some changes are made about when and how we can select a different > >> callback CPU for a callout callback. Try reading the updated timeout(9) > > > > I am not kernel guru and can't be draw a conclusion from manual page. > > > >> man manual page first. Maybe it answers your question. Else feel free to > >> ask here. > > > > As I understand performance for massive TCP connections (tens of > > thousands connections) will be same, no improvement, no degraded? > > (very high lock congestion on TCP timers working). > > Hi, > > There is no difference in memory footprint per TCP connection. > > There is no significant different in the amount of code executed when a > callout is started/stopped or reset. > > There might be a reduction in the number of times the spinlocks inside > the callout subsystem are locked/unlocked, due to some simplifications > made and checks for redundant locking. > > The changes are mainly about closing some races in the callout subsystem > and cornercases towards the TCP/IP stack which use callouts. > > There is a patch for the TCP/IP stack coming possibly next week to take > advantage of the new callout_drain_async() function. It is not ready > yet, and I'm waiting for the current callout patch to settle first. Thanks. I am going to try this patch in 10-STABLE branch.
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