From: David Vrabel <david.vrabel@citrix.com>
To: xen-devel@lists.xenproject.org
Cc: David Vrabel <david.vrabel@citrix.com>,
Jan Beulich <jbeulich@suse.com>,
Ian Campbell <ian.campbell@citrix.com>
Subject: passthrough: improve interrupt injection locking
Date: Fri, 23 Oct 2015 12:05:20 +0100 [thread overview]
Message-ID: <1445598322-22154-1-git-send-email-david.vrabel@citrix.com> (raw)
When injecting an interrupt for a passthrough device into a guest, the
per-domain event_lock is held, reducing performance when a guest has
many VCPUs and high interrupt rates.
By using a per-interrupt lock in the hot paths, this contention is
eliminated and performance improves (a bit).
For testing, a 32 VCPU guest with an NVME device assigned to it was
used. Continual reads with small (512 B) blocks were performed on all
32 hardware queues simultaneously.
* Lock profiling:
Before (elapsed: 60 s):
(XEN) [ 3321.143155] Domain 1 event_lock:
(XEN) [ 3321.143158] lock: 14411627(00000005:90714AEF),
block: 6658599(00000003:709F82BD)
After (elapsed: 60 s):
(XEN) [ 1253.921427] Domain 2 event_lock:
(XEN) [ 1253.921429] lock: 8287(00000000:01AE517C),
block: 67(00000000:000D4C3A)
* Aggregate performance:
MB/s
Before 60.8
After 68.4
David
next reply other threads:[~2015-10-23 11:05 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-23 11:05 David Vrabel [this message]
2015-10-23 11:05 ` [PATCHv1 1/2] passthrough: use per-interrupt lock when injecting an interrupt David Vrabel
2015-10-27 11:56 ` Jan Beulich
2015-10-28 20:18 ` Konrad Rzeszutek Wilk
2015-10-29 9:11 ` Jan Beulich
2015-10-30 14:45 ` Konrad Rzeszutek Wilk
2015-10-23 11:05 ` [PATCHv1 2/2] passthrough: improve locking when iterating over interrupts bound to VMs David Vrabel
2015-10-27 12:44 ` Jan Beulich
2015-10-27 13:11 ` David Vrabel
2015-10-28 20:42 ` Konrad Rzeszutek Wilk
2015-10-23 12:37 ` passthrough: improve interrupt injection locking Ian Campbell
2015-10-23 12:38 ` David Vrabel
2015-10-23 12:45 ` Ian Campbell
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