Date: Fri, 29 Oct 2010 18:31:21 +0400 From: "Alexander Zagrebin" <alexz@visp.ru> To: "'Andriy Gapon'" <avg@icyb.net.ua> Cc: freebsd-stable@freebsd.org Subject: RE: 8.1-STABLE: zfs and sendfile: problem still exists Message-ID: <1BDB4D1B02274CC8AA2DD5E68190CB5D@vosz.local> In-Reply-To: <4CCACDC0.7050802@icyb.net.ua> References: <3D1C350B94A44E5D95BAA1596D1EBF13@vosz.local><4CCABF73.8070707@icyb.net.ua><F28DAE02F7C94D25B0D86E3D27006C8B@vosz.local> <4CCACDC0.7050802@icyb.net.ua>
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> > I've tried the nginx with > > disabled sendfile (the nginx.conf contains "sendfile off;"): > > > > $ dd if=/dev/random of=test bs=1m count=100 > > 100+0 records in > > 100+0 records out > > 104857600 bytes transferred in 5.892504 secs (17795083 bytes/sec) > > $ fetch -o /dev/null http://localhost/test > > /dev/null 100% of 100 > MB 41 MBps > > $ fetch -o /dev/null http://localhost/test > > /dev/null 100% of 100 > MB 44 MBps > > $ fetch -o /dev/null http://localhost/test > > /dev/null 100% of 100 > MB 44 MBps > > > > I am really surprised with such a bad performance of sendfile. > Will you be able to profile the issue further? Yes. > I will also try to think of some measurements. A transfer rate is too low for the _first_ attempt only. Further attempts demonstrates a reasonable transfer rate. For example, nginx with "sendfile on;": $ dd if=/dev/random of=test bs=1m count=100 100+0 records in 100+0 records out 104857600 bytes transferred in 5.855305 secs (17908136 bytes/sec) $ fetch -o /dev/null http://localhost/test /dev/null 3% of 100 MB 118 kBps 13m50s^C fetch: transfer interrupted $ fetch -o /dev/null http://localhost/test /dev/null 100% of 100 MB 39 MBps If there was no access to the file during some time, then everything repeats: The first attempt - transfer rate is too low A further attempts - no problems Can you reproduce the problem on your system? -- Alexander Zagrebin
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