[PATCH] lglock: add read-preference local-global rwlock
oleg at redhat.com
Wed Mar 6 03:35:22 EST 2013
On 03/05, Lai Jiangshan wrote:
> On 03/03/13 01:06, Oleg Nesterov wrote:
> > On 03/02, Michel Lespinasse wrote:
> >> My version would be slower if it needs to take the
> >> slow path in a reentrant way, but I'm not sure it matters either :)
> > I'd say, this doesn't matter at all, simply because this can only happen
> > if we race with the active writer.
> It can also happen when interrupted. (still very rarely)
> __this_cpu_read() returns 0.
> arch_spin_trylock() fails
> slowpath, any nested will be slowpath too.
Yes sure. Or it can take the local lock after we already take the global
But the same can happen with FALLBACK_BASE, just because we need to take
a lock (local or global) first, then increment the counter.
> (I worries to much. I tend to remove FALLBACK_BASE now, we should
> add it only after we proved we needed it, this part is not proved)
Agreed, great ;)
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