Re: [Xen-devel] [RFC PATCH V4 11/18] Bump EVTCHNS_PER_BUCKET to 512

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Fri, 2013-03-15 at 18:15 +0000, David Vrabel wrote:
> On 05/03/13 12:30, Wei Liu wrote:
> > For 64 bit build and 3-level event channel and the original value of
> > EVTCHNS_PER_BUCKET (128), the space needed to accommodate d->evtchn would 
> > be 4
> > pages (PAGE_SIZE = 4096). Given that not every domain needs 3-level event
> > channel, this leads to waste of memory. Having EVTCHN_PER_BUCKETS to be 512
> > can occupy exact one page.
> 
> This makes the list of buckets a page in size but each bucket is now 4
> pages.
> 

I'm confused.

On 64 bit w/ FLASK enabled, sizeof(struct evtchn) = 18B, bucket size =
9216B = 2.25 pages; w/o FLASK enabled, sizeof(struct evtchn) = 10B,
bucket size = 5120B = 1.25 pages.

Yesterday I did start rewriting this bit to optimize space usage
though. :-)


Wei.


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