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>,
<konrad.wilk@oracle.com>
Subject: Re: [RESEND PATCH] xen/blkfront: increase the default value of xen_blkif_max_segments
Date: Wed, 21 Jan 2015 11:13:56 +0100 [thread overview]
Message-ID: <54BF7BE4.2080005@citrix.com> (raw)
In-Reply-To: <1421826963-6497-1-git-send-email-bob.liu@oracle.com>
El 21/01/15 a les 8.56, Bob Liu ha escrit:
> The default max-segments of indirect requests was 32, so IO operations with
> bigger block size(>32*4k) would be split and make performance drop.
>
> Nowadays backend device usually support 512k max_sectors_kb on desktop,
> and usually larger on server machines connected with high-end storage system.
> The default max size(128k) is not appropriate anymore, this patch increases it
> to 128(128*4k=512k).
>
> Signed-off-by: Bob Liu <bob.liu@oracle.com>
Looks fine to me, the Linux backend is also prepared to handle it
without any modifications. As I said in the last version, I would add
the following to the commit message:
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:[~2015-01-21 10:14 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-21 7:56 [RESEND PATCH] xen/blkfront: increase the default value of xen_blkif_max_segments Bob Liu
2015-01-21 10:13 ` Roger Pau Monné [this message]
2015-01-21 10:13 ` Roger Pau Monné
-- strict thread matches above, loose matches on Subject: below --
2015-01-21 7:56 Bob Liu
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