Date: Thu, 16 Sep 2010 11:53:47 +0400 From: cronfy <cronfy@gmail.com> To: freebsd-hackers@freebsd.org Subject: Re: is vfs.lookup_shared unsafe in 7.3? Message-ID: <AANLkTincNbk3wdcgRPsoeLLkKkSrFe_xcY6K-KPkGH-7@mail.gmail.com> In-Reply-To: <201009151509.49728.jhb@freebsd.org> References: <AANLkTinEje-%2B1P1n33YMKAaciaYHQH%2BdpwgX6UY1dOux@mail.gmail.com> <201009151509.49728.jhb@freebsd.org>
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>> Hello, >> >> Trying to overtake high server load (sudden peaks of 15%us/85%sy, LA > >> 40, very slow lstat() at these moments, looks like some kind of lock >> contention) I enabled vfs.lookup_shared=3D1 on two servers today. One is >> FreeBSD-7.3 kernel csup'ed and built Sep =A09 2010 and other is >> FreeBSD-7.3 csup'ed and built Jul 16 2010. >> >> The server with more fresh kernel is running nice and does not show >> high load anymore. But on the second server it did not help. More, >> after a few hours of work with vfs.lookup_shared=3D1 I noticed processes >> stucked in "ufs" state. I tried to kill them with no luck. Disabling >> vfs.lookup_shared freezed the whole system. >> >> So, is vfs.lookup_shared=3D1 unsafe in 7.3? Did it become more stable >> between 16 Jul and 9 Sep (is it the reason why first system is still >> running?), or should I expect that it will freeze in a near time too? >> >> Thanks in advance! > > No, 7.3 has a bug that can cause these hangs that is probably made worse = by > vfs.lookup_shared=3D1, but can occur even if it is disabled. =A0You want > these fixes applied (in order, one of them reverts part of another): Thank you for the fix and for the explanation, that's exactly what I wanted to know. Just to be sure: do these patches completely fix the bug with hangs (even without vfs.lookup_shared=3D1)? --=20 // cronfy
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