From: Olaf Hering <olaf@aepfle.de>
To: Andres Lagar-Cavilla <andres@lagarcavilla.org>
Cc: xen-devel@lists.xensource.com, adin@gridncetric.ca
Subject: Re: RFC: mem_event: use wait queue when ring is full
Date: Wed, 23 Nov 2011 17:49:18 +0100 [thread overview]
Message-ID: <20111123164918.GB6000@aepfle.de> (raw)
In-Reply-To: <6c2682114a95a003123344f552a2c64c.squirrel@webmail.lagarcavilla.org>
On Tue, Nov 22, Andres Lagar-Cavilla wrote:
> Olaf, two questions here
>
> - do you have any insight for events caused by foreign mappings? Those
> will be lost with a full ring, with or without wait queues
The callers of mem_event_check_ring() have to retry if the ring is full.
Thats what happens with p2m_mem_paging_populate(), the callers return
-ENOENT and expect a retry at some later point.
> - we have posted a patch (twice) previously, with changes to ring
> management, most importantly sending guest vcpus to sleep when space in
> the ring is < d->max_vcpus. I see these two patches as complementary. What
> is your take?
I'm not proposing to include my patch as is, because it has one issue:
wake_up will start all waiting vcpus even if there is just a single slot
free in the ringbuffer. You patch is better in this respect because only
a few will be started again.
I will send comments for it later.
Olaf
next prev parent reply other threads:[~2011-11-23 16:49 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <mailman.1126.1321998852.12970.xen-devel@lists.xensource.com>
2011-11-23 4:52 ` [PATCH 3 of 3] RFC: xenpaging: use waitqueue in ept_get Andres Lagar-Cavilla
2011-11-23 16:37 ` Olaf Hering
2011-11-23 17:36 ` Andres Lagar-Cavilla
2011-11-23 4:58 ` RFC: mem_event: use wait queue when ring is full Andres Lagar-Cavilla
2011-11-23 16:49 ` Olaf Hering [this message]
2011-11-23 17:17 ` Keir Fraser
2011-11-23 18:23 ` Olaf Hering
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