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Fix event test timer checks on kernels with HZ=100

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On kernels with HZ=100, the resolution of sleeps in poll() is
quite bad. Doing a precise check on the expiry time vs the
current time will thus often thing the timer has not expired
even though we're within 10ms of the expected expiry time. This
then causes another pointless sleep in poll() for <10ms. Timers
do not need to have such precise expiration, so we treat a timer
as expired if it is within 20ms of the expected expiry time. This
also fixes the eventtest.c test suite on kernels with HZ=100

* daemon/event.c: Add 20ms fuzz when checking for timer expiry
This commit is contained in:
Daniel P. Berrange 2009-12-02 11:53:42 +00:00
parent e15bf04465
commit 32f021f266
1 changed files with 6 additions and 1 deletions
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7
daemon/event.c
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@ -413,7 +413,12 @@ static int virEventDispatchTimeouts(void) {
if (eventLoop.timeouts[i].deleted || eventLoop.timeouts[i].frequency < 0)
continue;
if (eventLoop.timeouts[i].expiresAt <= now) {
/* Add 20ms fuzz so we don't pointlessly spin doing
* <10ms sleeps, particularly on kernels with low HZ
* it is fine that a timer expires 20ms earlier than
* requested
*/
if (eventLoop.timeouts[i].expiresAt <= (now+20)) {
virEventTimeoutCallback cb = eventLoop.timeouts[i].cb;
int timer = eventLoop.timeouts[i].timer;
void *opaque = eventLoop.timeouts[i].opaque;