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Date: Sat, 13 Apr 2013 13:24:10 +0300
From: Andriy Gapon <avg@FreeBSD.org>
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To: Adam Nowacki <nowakpl@platinum.linux.pl>
Subject: Re: ZFS slow reads for unallocated blocks
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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