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#1 2016-07-03 17:49:42

graysky
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From: :wq
Registered: 2008-12-01
Posts: 9,909
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Booting with scsi_mod.use_blk_mq=1 ... poor IO latency [solved]

When using scsi_mod.use_blk_mq=1, have you noticed poor latency when disk IO is in demand?  On a SATA3 HDD (Sragate Barracuda ST3000DM001), I am currently restoring a 500G backup via rsync (remote server on the LAN) and I can observe a massive performance hit as I use IO to the same drive for small copy tasks.  I did not experience this under the cfq IO scheduler.  I also noticed it when zeroing out some free space on the same HDD using the dm-crypt wipte method.  Others care to comment?

EDIT: seems this is to be expected.

Last edited by graysky (2016-08-07 13:33:00)


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#2 2016-08-02 11:18:50

nefelim4ag
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From: Minsk
Registered: 2014-01-05
Posts: 3
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Re: Booting with scsi_mod.use_blk_mq=1 ... poor IO latency [solved]

@graysky, blk-mq disable io schedulers, so it's expected on HDD

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#3 2016-08-07 11:04:34

graysky
Wiki Maintainer
From: :wq
Registered: 2008-12-01
Posts: 9,909
Website

Re: Booting with scsi_mod.use_blk_mq=1 ... poor IO latency [solved]

Ah!  Seems like another method to enabled it for only SSDs would be needed then... I struck out googling for this...
EDIT: https://mahmoudhatem.wordpress.com/2016 … el-blk-mq/

Last edited by graysky (2016-08-10 05:36:23)


CPU-optimized Linux-ck packages @ Repo-ck  • AUR packagesZsh and other configs

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