Date: Mon, 02 Nov 2009 12:55:34 +0100 From: Ivan Voras <ivoras@freebsd.org> To: freebsd-stable@freebsd.org Subject: Re: Performance issues with 8.0 ZFS and sendfile/lighttpd Message-ID: <hcmhbj$40s$1@ger.gmane.org> In-Reply-To: <4AEEBD4B.1050407@quip.cz> References: <772532900-1257123963-cardhu_decombobulator_blackberry.rim.net-1402739480-@bda715.bisx.prod.on.blackberry> <hcma4s$c49$1@ger.gmane.org> <4AEEBD4B.1050407@quip.cz>
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Miroslav Lachman wrote: > Ivan Voras wrote: >> gnukix@alltel.blackberry.com wrote: >>> I can send in more documentation later but I am seeing severe zfs >>> performance issues with lighttpd. Same machine using UFS will push >>> 1gbit or more but same content and traffic load can not hit 200mbit. >>> Ufs does around 3 megabytes/sec IO at 800mbit network but zfs pushes >>> the disks into the ground with 50+ megabytes/sec dusk i/o. No >>> compression no atime no checksums on zfs and still same IO levels. Ufs >>> with soft updates and atime on. Orders of magnitude more disk IO... >>> Like zfs isn't using cache or isn't coalescing disk reads or both. >>> Has anyone else seen this or have any recommendations? Lighttpd config >>> remains exactly the same as well FYI. Only difference is ufs vs zfs. >> >> AFAIK, ZFS is incompatible (currently) with some advanced VM operations >> (like mmap, and I think sendfile relies on the same mechanism as mmap), >> so that could be a cause of the slowdown. Though I'm surprised you can >> only get 200 MBit/s - that's 25 MB/s and I think that even with multiple >> memcpy-ing data around the kernel you should be able to get hundreds of >> MB/s on newer hardware (which normally really can achieve tens of >> gigabytes/s of sustained memory access). > > I have more strange issue with Lighttpd in jail on top of ZFS. Lighttpd > is serving static content (mp3 downloads thru flash player). Is runs > fine for relatively small number of parallel clients with bandwidth > about 30 Mbps, but after some number of clients is reached (about 50-60 > parallel clients) the throughput drops down to 6 Mbps. > > I can server hundereds of clients on same HW using Lighttpd not in jail > and UFS2 with gjournal instead of ZFS reaching 100 Mbps (maybe more). > > I don't know if it is ZFS or Jail issue. Do you have actual disk IO or is the vast majority of your data served from the caches? (actually - the same question to the OP)
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