Re: kevent and wait time?
Re: kevent and wait time?
- Subject: Re: kevent and wait time?
- From: Dave Zarzycki <email@hidden>
- Date: Mon, 3 Apr 2006 06:04:42 -0700
kqueue is not select/poll.
To better understand what I mean by that, consider calling kevent()
once per FD you allocate and only use kevent() to add to the kqueue.
Then, as a part of your event loop, only fetch one event with kevent()
and process it.
davez
On Apr 2, 2006, at 9:42 PM, email@hidden wrote:
Hello, all ...
I seem to have found my problem with my kqueue / kevent code, but it
ends up perplexing me even more. The context is this: i'm seeing
how far kqueues can scale in comparison to select() regarding # of
active, simultaneous connections to a server -- C10K stuff,
basically. I've written some C++ code that tests the kqueue by
adding a specified number of descriptors to it, waiting for events
from those descriptors, and seeing how many events from how many
descriptors I can process in some configurable amount of time.
The thing is, my code only seems to work if I specify NULL for the
timeout to kevent() -- kevent() comes back when one of the
descriptors i've added to it indeed has something to tell me.
However, if I specify a timeout of 0 (as a timeval), then kevent()
comes back right away, telling me about some event on some
descriptor i've never heard of (and didn't add to the queue) -- the
descriptor is a really big number, which initially made me think
"pointer bug", but simply changing the timeout to NULL (indefinite),
makes everything work, which makes me thinkg "ok, so it's not a
pointer bug."
The relevant piece of code follows -- it's really short :-)
// Test() tesks the kqueue by processing any notifications we
get ...
int Test( int iLimit )
{
int iReturn = 0;
for ( int iIndex = 0; iIndex < iLimit; iIndex ++ )
{
struct kevent kLEvent;
struct timespec timeToWait = { 0 };
int iNev = kevent( iKQ, pkEvents,
iNumberOfConnectionsCreated, &kLEvent, 1, NULL /*&timeToWait*/ );
testModule.Process( kLEvent, iNev );
}
testModule.ReportTestResults();
return iReturn;
}
I don't get it. The man page for kevent doesn't say anything about
a non-NULL timeout (well, it's 0, but it's not NULL) affecting how
kevent() works ... what am I doing wrong?
Regards,
John
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