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List:       freebsd-hackers
Subject:    ZFS sends TIRMs to agressively? (Was: Painfully slow compilation (read: "make buildworld buildkernel
From:       Lev Serebryakov <lev () FreeBSD ! org>
Date:       2018-12-08 19:09:43
Message-ID: 1102394497.20181208220943 () serebryakov ! spb ! ru
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Hello Lev,

Saturday, December 8, 2018, 7:58:37 PM, you wrote:

>> Can you please narrow the problem down to a specific kernel revision?
>  I'm still not sure it is software or hardware problem.
 Looks like Samsung 850 EVO doesn't like TRIMs sent by ZFS (and I've thought
it is good SSD, consumer-grade, but really good one!).

 I've tuned down TRIMs with

vfs.zfs.per_txg_dirty_frees_percent=10
vfs.zfs.free_max_blocks=1000
vfs.zfs.vdev.trim_max_active=4

And it MOSTLY solved problem: there are some freezing from time to time (and
strange consumption of CPU by low-profile threads) with these settings.

 When I've disabled TRIM completely all freezes are gone, and low-profile
threads consume tenths of percent of CPU, as it is intended.

-- 
Best regards,
 Lev                            mailto:lev@FreeBSD.org

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