Re: [CRYPTO]: Only reschedule if !in_atomic()

From: Bill Davidsen
Date: Tue May 24 2005 - 08:38:51 EST


Andrew Morton wrote:
Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> wrote:

Perhaps we should code this into the crypto API instead? For instance,
we can have a tfm flag that says whether we can sleep or not.


Are you sure it's actually needed? Have significant scheduling latencies
actually been observed?

Bear in mind that anyone who cares a lot about latency will be running
CONFIG_PREEMPT kernels, in which case the whole thing is redundant anyway. I generally take the position that if we're going to put a scheduling point
into a non-premept kernel then it'd better be for a pretty bad latency
point - more than 10 milliseconds, say.

People do run crypto on old slow machines, and also laptops configured to use as little power as possible. I wouldn't be surprised if latencies got in the >10ms range pretty regularly on some systems which are pretty mainstream.

Just my read on it, if a flag will prevent deadlock without relying on callers doing the right thing, that's probably a desirable change WRT future stability.
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