Date: Tue, 6 Dec 2016 22:26:21 +0200 From: Alexander Motin <mav@FreeBSD.org> To: freebsd-fs@FreeBSD.org Cc: Alex Tutubalin <lexa@lexa.ru>, Andriy Gapon <avg@FreeBSD.org> Subject: Re: 11-STABLE vs 11.0-RELENG test Message-ID: <8b4ba98d-03d3-f671-33b2-ed12d3b4fb7c@FreeBSD.org>
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On 06/12/2016 18:17, Alex Tutubalin wrote: > Followup, same box as in 1st message, but with different HBA and 5 HDD: > > Summary: > 1) read speed depends on 'on-disk' data, not by code used while read. > 2) FreeBSD 11.0-releng (svn up today) creates 'fast' big files (420+ Mb/s read > speed) > 3) FreeBSD 11-STABLE creates 'slow' big files. (~200 Mb/s) > 4) zfs send slow-dataset | zfs recv (under 11.0-releng) creates > 'intermediate' files (320Mb/s) > 5) file copy slow-file ... (under 11.0-releng) creates fast copy (400+Mb/s) > > So, ZFS write code in 11-STABLE looks broken. I've reproduced this issue with quick test on my lab system configured with 12-disk RAIDZ2 pool. I've measured write and read back (with and without prefetch) speeds for pool recreated on different FreeBSD head revisions: r309625 r305456 r305330 r305322 write 702 701 1115 1120 read w/ pref 232 228 518 512 read w/o pref 128 126 242 240 I suspect we could obtain the problem here: r305331 | mav | 2016-09-03 13:04:37 +0300 (сб, 03 сент. 2016) | 45 lines MFV r304155: 7090 zfs should improve allocation order and throttle allocations I'll take closer look on that change tomorrow. -- Alexander Motin
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