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Date: Mon, 22 Feb 2016 13:58:18 -0900
From: Kent Overstreet <kent.overstreet@gmail.com>
To: Ming Lei <ming.lei@canonical.com>
Cc: Ming Lin-SSI <ming.l@ssi.samsung.com>, Pavel Machek <pavel@ucw.cz>,
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Subject: Re: 4.4-final: 28 bioset threads on small notebook
Message-ID: <20160222225818.GA2675@kmo-pixel>
References: <20151211140841.GA22873@redhat.com>
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 <20160220200432.GB22120@amd>
 <20160220203856.GB27149@redhat.com>
 <20160220205519.GA14108@amd>
 <20160221041540.GA24735@kmo-pixel>
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On Sun, Feb 21, 2016 at 05:40:59PM +0800, Ming Lei wrote:
> On Sun, Feb 21, 2016 at 2:43 PM, Ming Lin-SSI <ming.l@ssi.samsung.com> wrote:
> >>-----Original Message-----
> >
> > So it's almost already "per request_queue"
> 
> Yes, that is because of the following line:
> 
> q->bio_split = bioset_create(BIO_POOL_SIZE, 0);
> 
> in blk_alloc_queue_node().
> 
> Looks like this bio_set doesn't need to be per-request_queue, and
> now it is only used for fast-cloning bio for splitting, and one global
> split bio_set should be enough.

It does have to be per request queue for stacking block devices (which includes
loopback).