On Mon, Jun 30, 2014 at 01:04:09PM +0200, Michal Skrivanek wrote: > Hi, > just thinking about the recent stats hook[1] by Dima and scale, > It is a very nice hook and quite useful for the scale testing - ( though when > focus is on engine I'd suggest to use FakeVDSM instead to eliminate all the > bottlenecks on VDSM side.) > > One issue I see - since this is a very high-profile call, every 15s time > number of VMs - is with the hook invocation. Currently the hook mechanism > always go through the hooks dit and does stat() call to see script is there > or not… > it certainly doesn't matter on small scale but when the system is on the edge > every IO on local FS cost something….
> Would be nice if the hook mechanism is enhanced in general, figure out which > hooks are relevant only at the startup and don't waste time passing domainXML > every single time when the hook is not there But a caching mechanism for hook scripts costs "something", too (code size, bugs, simplicty of testing new script). Before complicating the mechanism, I'd rather see numbers: how much would be saved? I would guess that filesystem caching already shaves costs of stat()s. Writing domxml to a memory-map file before starting a vm may be insignificant, too. Dan. _______________________________________________ Devel mailing list [email protected] http://lists.ovirt.org/mailman/listinfo/devel
