Re: Lockless uidinfo.

* Pawel Jakub Dawidek <pjd@xxxxxxxxxxx> [070818 07:59] wrote:
On Sat, Aug 18, 2007 at 07:23:37AM -0700, Alfred Perlstein wrote:
* Pawel Jakub Dawidek <pjd@xxxxxxxxxxx> [070818 05:31] wrote:
Hi.

The patch below remove per-uidinfo locks:

http://people.freebsd.org/~pjd/patches/uidinfo_lockless.patch

In uifree() is it ok to manually check the refcount for 0?

I'm gussing the hashmtx is used as a barrier?

Yes, to lookup uidinfo you need to hold uihashtbl_mtx mutex, so once you
hold it and ui_ref is 0, noone will be able to reference it, because it
has to wait to look it up.

And the field doesn't need to be volatile to prevent cached/opportunitic
reads?


--
- Alfred Perlstein
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