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[Qemu-devel] [PATCH v2 1/3] Do not drop global mutex for polled main loo
From: |
Jan Kiszka |
Subject: |
[Qemu-devel] [PATCH v2 1/3] Do not drop global mutex for polled main loop runs |
Date: |
Mon, 11 Apr 2011 22:27:42 +0200 |
From: Jan Kiszka <address@hidden>
If we call select without a timeout, it's more efficient to keep the
global mutex locked as we may otherwise just play ping pong with a
vcpu thread contending for it. This is particularly important for TCG
mode where we run in lock-step with the vcpu thread.
Signed-off-by: Jan Kiszka <address@hidden>
---
vl.c | 10 ++++++++--
1 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/vl.c b/vl.c
index 68c3b53..b7bbed8 100644
--- a/vl.c
+++ b/vl.c
@@ -1314,9 +1314,15 @@ void main_loop_wait(int nonblocking)
qemu_iohandler_fill(&nfds, &rfds, &wfds, &xfds);
slirp_select_fill(&nfds, &rfds, &wfds, &xfds);
- qemu_mutex_unlock_iothread();
+ if (timeout > 0) {
+ qemu_mutex_unlock_iothread();
+ }
+
ret = select(nfds + 1, &rfds, &wfds, &xfds, &tv);
- qemu_mutex_lock_iothread();
+
+ if (timeout > 0) {
+ qemu_mutex_lock_iothread();
+ }
qemu_iohandler_poll(&rfds, &wfds, &xfds, ret);
slirp_select_poll(&rfds, &wfds, &xfds, (ret < 0));
--
1.7.1
- [Qemu-devel] [PATCH v2 0/3] io-thread optimizations, Jan Kiszka, 2011/04/11
- [Qemu-devel] [PATCH v2 3/3] Do not kick vcpus in TCG mode, Jan Kiszka, 2011/04/11
- [Qemu-devel] [PATCH v2 2/3] Poll main loop after I/O events were received, Jan Kiszka, 2011/04/11
- [Qemu-devel] [PATCH v2 1/3] Do not drop global mutex for polled main loop runs,
Jan Kiszka <=
- Re: [Qemu-devel] [PATCH v2 0/3] io-thread optimizations, Paolo Bonzini, 2011/04/12
- Re: [Qemu-devel] [PATCH v2 0/3] io-thread optimizations, Aurelien Jarno, 2011/04/13
- Re: [Qemu-devel] [PATCH v2 0/3] io-thread optimizations, Aurelien Jarno, 2011/04/25
- Re: [Qemu-devel] [PATCH v2 0/3] io-thread optimizations, Jan Kiszka, 2011/04/26