Date: Thu, 12 Jan 2012 12:29:57 +0200 From: Andriy Gapon <avg@FreeBSD.org> To: lev@FreeBSD.org Cc: freebsd-net@FreeBSD.org, freebsd-current@FreeBSD.org, jhb@FreeBSD.org Subject: Re: SCHED_ULE / NetGraph interaction broken somwhere between r227874 and r229818 Message-ID: <4F0EB625.3000905@FreeBSD.org> In-Reply-To: <1699441022.20120112140525@serebryakov.spb.ru> References: <1379921442.20120112133112@serebryakov.spb.ru> <4F0EADE1.9070803@FreeBSD.org> <1699441022.20120112140525@serebryakov.spb.ru>
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on 12/01/2012 12:05 Lev Serebryakov said the following: > Hello, Andriy. > You wrote 12 января 2012 г., 13:54:41: > >>> Switching to 4BSD helps. 4BSD works as usual: all CPU time is >>> interrupts and network thread, system is responsive under heaviest load, >>> normal operations of DNS, DHCP and hostapd. >> How reproducible is this result? > 100% > >> In other words, have you definitely ruled out all other factors besides the >> scheduler? > > I have two almost-identical NanoBSD images which differs in one line in kernel > config -- option about scheduler. Worlds are exactly the same, only kernels were > rebuilt. > > Alexander Motin suggests, that switching scheduler could slightly > change stack consumption, which triggers switching to ng_queue > instead of direct calls. > > Really, here is diff between "md5" of all files of one and other > images: Well, I mostly meant things like uptime, load level and pattern, etc. But what mav says makes sense. Also I remember seeing some very old reports about some strange issues with SCHED_ULE and dummynet. Some links that I found: http://lists.freebsd.org/pipermail/freebsd-stable/2008-October/046332.html http://dadv.livejournal.com/139366.html#cutid1 Given the last link, I wonder if binding the ng_queue thread to a particular CPU would change anything. > blob# diff ~lev/bsd-image.md5sums ~lev/ule-image.md5sums > 74c74 > < MD5 (./boot/kernel/kernel) = 3bb0dd757628b5065d27ee5e7fc22eb3 > --- >> MD5 (./boot/kernel/kernel) = 5ba379d2c73e1277566f4bbcb618a9f2 > 618c618 > < MD5 (./conf/base/var/log/userlog) = a827af82c1f780687706b19c7d94b29e > --- >> MD5 (./conf/base/var/log/userlog) = fc289b66ae6cb23f9b24b694bf12157b > 15678c15678 > < MD5 (./var/log/userlog) = a827af82c1f780687706b19c7d94b29e > --- >> MD5 (./var/log/userlog) = fc289b66ae6cb23f9b24b694bf12157b > -- Andriy Gapon
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