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From: Christoph Nelles <evilazrael@evilazrael.de>
To: device-mapper development <dm-devel@redhat.com>
Subject: Re: DM-Cache Writeback & Direct IO?
Date: Thu, 09 Jul 2015 17:51:50 +0200	[thread overview]
Message-ID: <559E9896.3040305@evilazrael.de> (raw)
In-Reply-To: <CAEZ+n-hF2EUPAHYC98ao0x_Q2nWXFodaxXkBqjg8ZvpqNviVKQ@mail.gmail.com>


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Hi Leonardo,

I am aware that sequential IO is routed directly to the backing device. 
And I also played with the parameters like sequential_threshold and the 
write_promote_adjustment introduced in 3.14.
To test this i ran ./fio --name=test --filename=/dev/mapper/dmcache  
--rw=randwrite  --filesize=16G --bs=64k --ioengine=libaio --direct=1 
--iodepth=1000 in a endless loop.

Regards

Christoph


Am 08.07.2015 um 19:55 schrieb Leonardo Santos:
> Are you using sequential or random workload?
> It's important, since DMCache bypasses sequential I/O based on theshold.
>
>
> --
> dm-devel mailing list
> dm-devel@redhat.com
> https://www.redhat.com/mailman/listinfo/dm-devel


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  reply	other threads:[~2015-07-09 15:51 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <9E0DEE10BA62134F89BB5A513CA84BC3A1A6B5CA@MAILSERVER01.trt9a.local>
     [not found] ` <CAEZ+n-j_9QGWi7pdZY71VAmF-tnuRWb_8neWBd3iKMTm-yQU1A@mail.gmail.com>
2015-07-08 17:55   ` DM-Cache Writeback & Direct IO? Leonardo Santos
2015-07-09 15:51     ` Christoph Nelles [this message]
2015-07-08  9:03 Christoph Nelles
2015-07-08 14:48 ` Joe Thornber
2015-07-09 16:51   ` Christoph Nelles
2015-07-21 13:51   ` Christoph Nelles

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