Messages in this thread | | | From | "Jason A. Donenfeld" <> | Date | Fri, 4 Feb 2022 15:11:34 +0100 | Subject | Re: [PATCH v2] random: remove batched entropy locking |
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Hi Sebastian,
On Fri, Feb 4, 2022 at 3:02 PM Sebastian Andrzej Siewior <bigeasy@linutronix.de> wrote: > The commit in tree you cited is b43db859a36cb553102c9c80431fc44618703bda. > It does not mention anything regarding faster nor the performance > improvement and conditions (hoth path, etc). It still has a stable tag.
It dropped the Cc: stable@. It still has the Fixes:. I can get rid of the Fixes: too. I'll improve that message a bunch for a potential v3.
> > Maybe it'd be best to retain the spinlock_t, which will amount to > > disabling interrupts on !PREEMPT_RT, since it'll never be contended, > > but will turn into a mutex on PREEMPT_RT, where it'll do the right > > thing from an exclusivity perspective. Would this be reasonable? > > what does retain the spinlock_t mean since we already have a spinlock_t?
The idea would be to keep using spinlock_t like we do now -- no change there -- but move to using this atomic generation counter so that there's never any contention. Actually, though, I worry that that approach would throw out the gains we're getting by chucking the spinlock in the first place.
What if we keep a spinlock_t there on PREEMPT_RT but stick with disabling interrupts on !PREEMPT_RT? I wish there was a solution or an API that amounted to the same thing so there wouldn't need to be an #ifdef, but I don't know what that'd be.
Jason
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