Date: Wed, 9 Aug 2006 10:44:31 +1000 From: Q <qdolan@gmail.com> To: Eric Anderson <anderson@centtech.com> Cc: freebsd-fs@freebsd.org Subject: Re: Problem with ufs not releasing vm_pages on busy volume. (soft updates related) Message-ID: <B1C737F3-28C3-48C4-B81B-1ED90E39222A@gmail.com> In-Reply-To: <44D8B6D6.6070209@centtech.com> References: <A05A5F4D-27B0-410B-A32D-0432D22D5A00@gmail.com> <06530464-7491-4BC1-97C7-87285B03F2EB@gmail.com> <44D8B6D6.6070209@centtech.com>
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On 09/08/2006, at 2:07 AM, Eric Anderson wrote: > On 08/08/06 00:14, Q wrote: >> On 02/08/2006, at 8:10 PM, Q wrote: >>> I have a problem that seems to be related to something ufs >>> related not releasing some vm_pages on busy filesystems. I have >>> two servers running PostgreSQL, one running 6.0-RELEASE, the >>> other 6.1-RELEASE. Both are under the same (fairly heavy) load, >>> performing the same operations in bursts every five minutes. The >>> filesystems in question are 450-500Gig, each server using a >>> different brand of RAID card, they both have soft-updates enabled. >>> >>> The problem is that both servers are seeing an accumulation of >>> about 100Mb of active pages per day (looking at >>> vm.stats.vm.v_active_count) that never get released. The only >>> way to release these pages is to unmount the filesystem and >>> remount it. Failing to do this results in the server eventually >>> locking up. >>> >>> If someone could provide me with some direction on how to go >>> about tracking down what might be causing this to happen it >>> would be much appreciated. >> I have narrowed the cause of this issue down further to something >> to do with soft updates. If I turn off soft updates for the >> filesystem hosting the database the system no longer accumulates >> active vm_pages constantly. Instead for accumulating 100Mb a day >> of active vm pages until all memory is consumed, it will hover >> around 50-60Mb with soft updates disabled. >> If someone familiar with the softupdates code is willing to help >> me pinpoint the cause of this problem it would be much appreciated. > > > Is it possible for you to upgrade to the latest 6-STABLE branch, > just to make sure that the issue hasn't been fixed already? I did a buildworld on one the machine running 6.0-RELEASE last night. I just have to schedule some downtime to do the upgrade sometime today. Having two identical servers has it's advantages. > Is there any way to reproduce this on another box for testing? (I > assume not, due to the nature of these things) I think this bug is very circumstance specific, and my database design just happens to exercise the bug. The fact that I have two identical servers experiencing exactly the same problem does helps narrow the field of possibilities, but the servers are my no means "expendable". > Also - I wonder if doing a snapshot on the filesystem would flush > out the pages - is that something you can try? Possibly. I will see what I can do. -- Seeya...Q -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- _____ / Quinton Dolan - qdolan@gmail.com __ __/ / / __/ / / / __ / _/ / / Gold Coast, QLD, Australia __/ __/ __/ ____/ / - / Ph: +61 419 729 806 _______ / _\
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