Date: Fri, 6 Nov 2009 23:31:51 -0800 From: Jeremy Chadwick <freebsd@jdc.parodius.com> To: Miroslav Lachman <000.fbsd@quip.cz> Cc: freebsd-stable@freebsd.org, Ivan Voras <ivoras@freebsd.org>, Thomas Backman <serenity@exscape.org> Subject: Re: Performance issues with 8.0 ZFS and sendfile/lighttpd Message-ID: <20091107073151.GA60756@icarus.home.lan> In-Reply-To: <4AF4A608.4020706@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> <hcmhbj$40s$1@ger.gmane.org> <4AEEDB3B.5020600@quip.cz> <hcmndo$q4e$1@ger.gmane.org> <4AF46CA9.1040904@quip.cz> <EB4B2182-4170-4C27-B462-6C869049219B@exscape.org> <4AF4A608.4020706@quip.cz>
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On Fri, Nov 06, 2009 at 11:41:12PM +0100, Miroslav Lachman wrote: > Thomas Backman wrote: > >On Nov 6, 2009, at 7:36 PM, Miroslav Lachman wrote: > > > >>Ivan Voras wrote: > >>>Miroslav Lachman wrote: > >>>>Ivan Voras wrote: > >>>>>Miroslav Lachman wrote: > >>>> > >>>>[..] > >>>> > >>>>>>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) > >>>> > >>>>I had ZFS zpool as mirror of two SATA II drives (500GB) and in the > >>>>peak iostat (or systat -vm or gstat) shows about 80 tps / 60% busy. > >>>> > >>>>In case of UFS, I am using gmirrored 1TB SATA II drives working nice > >>>>with 160 or more tps. > >>>> > >>>>Both setups are using FreeBSD 7.x amd64 with GENERIC kernel, 4GB of > >>>>RAM. > >>>> > >>>>As the ZFS + Lighttpd in jail was unreliable, I am no longer using it, > >>>>but if you want some more info for debuging, I can set it up again. > >>> > >>>For what it's worth, I have just set up a little test on a production > >>>machine with 3 500 GB SATA drives in RAIDZ, FreeBSD 7.2-RELEASE. The > >>>total data set is some 2 GB in 5000 files but the machine has only 2 GB > >>>RAM total so there is some disk IO - about 40 IOPS per drive. I'm also > >>>using Apache-worker, not lighty, and siege to benchmark with 10 > >>>concurrent users. > >>> > >>>In this setup, the machine has no problems saturating a 100 Mbit/s link > >>>- it's not on a LAN but the latency is close enough and I get ~~ 11 > >>>MB/s. > >> > >>[...] > >>/boot/loader.conf: > >> > >>## eLOM support > >>hw.bge.allow_asf="1" > >>## gmirror RAID1 > >>geom_mirror_load="YES" > >>## ZFS tuning > >>vm.kmem_size="1280M" > >>vm.kmem_size_max="1280M" > >>kern.maxvnodes="400000" > >>vfs.zfs.prefetch_disable="1" > >>vfs.zfs.arc_min="16M" > >>vfs.zfs.arc_max="128M" > > >I won't pretend to know much about this area, but your ZFS values here > >are very low. May I assume that they are remnants of the times when the > >ARC grew insanely large and caused a kernel panic? > >You're effectively forcing ZFS to not use more than 128MB cache, which > >doesn't sound like a great idea if you've got 2+ GB of RAM. I've had no > >trouble without any tuning whatsoever on 2GB for a long time now. The > >kmem lines can probably be omitted if you're on amd64, too (the default > >value for kmem_size_max is about 307GB on my machine). > > Yes, loader values are one year old when I installed this machine. > But I think auto tuning was commited after 7.2-RELEASE by Kip Macy, > so some of them are still needed or am I wrong? (this is > 7.2-RELEASE). ... We don't know, because none of the individuals who are maintaining ZFS at this point in time have actually responded to this question. http://lists.freebsd.org/pipermail/freebsd-stable/2009-October/052256.html The community really needs an official answer to this question, and one from those familiar with the code. -- | Jeremy Chadwick jdc@parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, USA | | Making life hard for others since 1977. PGP: 4BD6C0CB |
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