linux-kernel - Re: [PATCH] loop: Add PF_LESS_THROTTLE to block/loop device thread.

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Message-ID: <CACVXFVN8tTYjidbdSJsEpnWcUccvyd-xsvCpJ9vDMtvs+ciCzQ@mail.gmail.com>
Date:   Wed, 5 Apr 2017 13:13:23 +0800
From:   Ming Lei <tom.leiming@...il.com>
To:     NeilBrown <neilb@...e.com>
Cc:     Christoph Hellwig <hch@...radead.org>, Jens Axboe <axboe@...com>,
        linux-block <linux-block@...r.kernel.org>,
        linux-mm <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] loop: Add PF_LESS_THROTTLE to block/loop device thread.

On Wed, Apr 5, 2017 at 12:27 PM, NeilBrown <neilb@...e.com> wrote:
> On Tue, Apr 04 2017, Christoph Hellwig wrote:
>
>> Looks fine,
>>
>> Reviewed-by: Christoph Hellwig <hch@....de>
>>
>> But if you actually care about performance in any way I'd suggest
>> to use the loop device in direct I/O mode..
>
> The losetup on my test VM is too old to support that :-(
> I guess it might be time to upgraded.
>
> It seems that there is not "mount -o direct_loop" or similar, so you
> have to do the losetup and the mount separately.  Any thoughts on

I guess the 'direct_loop' can be added into 'mount' directly? but not familiar
with mount utility.

> whether that should be changed ?

There was sysfs interface for controling direct IO in the initial
submission, but
looks it was reviewed out, :-)


Thanks,
Ming Lei