From: Chris Friesen <chris.friesen@windriver.com>
To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Josh Durgin <josh.durgin@inktank.com>,
Jeff Cody <jcody@redhat.com>,
Linux Virtualization <virtualization@lists.linux-foundation.org>,
"Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: help? looking for limits on in-flight write operations for virtio-blk
Date: Tue, 26 Aug 2014 23:43:54 -0600 [thread overview]
Message-ID: <53FD701A.4060204@windriver.com> (raw)
In-Reply-To: <53FCA088.7050108@windriver.com>
On 08/26/2014 08:58 AM, Chris Friesen wrote:
> What I'd like to see (and may take a stab at implementing) is a cap on
> either inflight bytes or inflight IOPS. One complication is that this
> requires hooking into the completion path to update the stats (and
> possibly unblock the I/O code) when an operation is done.
Well, it looks like I won't be taking a stab at this after all.
It seems that modifying qemu to call mallopt() to set the trim/mmap
thresholds to 128K is enough to minimize the increase in RSS and also
drop it back down after an I/O burst. For now this looks like it should
be sufficient for our purposes.
I'm actually a bit surprised I didn't have to go lower, but it seems to
work for both "dd" and dbench testcases so we'll give it a try.
Chris
prev parent reply other threads:[~2014-08-27 5:43 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-25 19:42 help? looking for limits on in-flight write operations for virtio-blk Chris Friesen
2014-08-26 10:34 ` Stefan Hajnoczi
2014-08-26 14:58 ` Chris Friesen
2014-08-27 5:43 ` Chris Friesen [this message]
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