Date: Sat, 13 Apr 2013 13:24:10 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: Adam Nowacki <nowakpl@platinum.linux.pl> Cc: freebsd-fs@FreeBSD.org Subject: Re: ZFS slow reads for unallocated blocks Message-ID: <5169324A.3080309@FreeBSD.org> In-Reply-To: <51689A2C.4080402@platinum.linux.pl> References: <5166EA43.7050700@platinum.linux.pl> <5167B1C5.8020402@FreeBSD.org> <51689A2C.4080402@platinum.linux.pl>
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on 13/04/2013 02:35 Adam Nowacki said the following: > http://tepeserwery.pl/nowak/freebsd/zfs_sparse_optimization.patch.txt > > Does it look sane? It's hard to tell from a quick look since they change is not small. What is your idea of the problem and the fix? > On 2013-04-12 09:03, Andriy Gapon wrote: >> >> ENOTIME to really investigate, but here is a basic profile result for those >> interested: >> kernel`bzero+0xa >> kernel`dmu_buf_hold_array_by_dnode+0x1cf >> kernel`dmu_read_uio+0x66 >> kernel`zfs_freebsd_read+0x3c0 >> kernel`VOP_READ_APV+0x92 >> kernel`vn_read+0x1a3 >> kernel`vn_io_fault+0x23a >> kernel`dofileread+0x7b >> kernel`sys_read+0x9e >> kernel`amd64_syscall+0x238 >> kernel`0xffffffff80747e4b >> >> That's where > 99% of time is spent. >> > -- Andriy Gapon
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