From: "Roger Pau Monné" <roger.pau@citrix.com>
To: Bob Liu <bob.liu@oracle.com>, <xen-devel@lists.xen.org>
Cc: <david.vrabel@citrix.com>, <linux-kernel@vger.kernel.org>
Subject: Re: [Xen-devel] [PATCH] xen/blkfront: increase the default value of xen_blkif_max_segments
Date: Tue, 16 Dec 2014 11:32:31 +0100 [thread overview]
Message-ID: <54900A3F.7070300@citrix.com> (raw)
In-Reply-To: <1418724696-23922-1-git-send-email-bob.liu@oracle.com>
El 16/12/14 a les 11.11, Bob Liu ha escrit:
> The default maximum value of segments in indirect requests was 32, IO
> operations with bigger block size(>32*4k) would be split and performance start
> to drop.
>
> Nowadays backend device usually support 512k max_sectors_kb on desktop, and
> may larger on server machines with high-end storage system.
> The default size 128k was not very appropriate, this patch increases the default
> maximum value to 128(128*4k=512k).
This looks fine, do you have any data/graphs to backup your reasoning?
I would also add to the commit message that this change implies we can
now have 32*128+32 = 4128 in-flight grants, which greatly surpasses the
default amount of persistent grants blkback can handle, so the LRU in
blkback will kick in.
Roger.
next prev parent reply other threads:[~2014-12-16 10:32 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-16 10:11 [PATCH] xen/blkfront: increase the default value of xen_blkif_max_segments Bob Liu
2014-12-16 10:32 ` Roger Pau Monné
2014-12-16 10:32 ` Roger Pau Monné [this message]
2014-12-17 8:18 ` Bob Liu
2014-12-17 8:18 ` [Xen-devel] " Bob Liu
2014-12-17 16:13 ` Konrad Rzeszutek Wilk
2014-12-17 16:13 ` [Xen-devel] " Konrad Rzeszutek Wilk
2014-12-17 16:34 ` David Vrabel
2014-12-17 16:34 ` [Xen-devel] " David Vrabel
2014-12-17 16:47 ` Konrad Rzeszutek Wilk
2014-12-17 16:47 ` Konrad Rzeszutek Wilk
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