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Do not drop global mutex for polled main loop runs

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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 <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Jan Kiszka 2011-08-22 17:46:01 +02:00 committed by Anthony Liguori
parent 6e23063c46
commit 200668ba08
1 changed files with 8 additions and 2 deletions
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10
vl.c
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@ -1349,9 +1349,15 @@ 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));