| Date | Wed, 18 Jul 2018 14:22:07 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 08/10] psi: pressure stall information for CPU, memory, and IO |
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On Wed, Jul 18, 2018 at 02:03:18PM +0200, Peter Zijlstra wrote: > On Thu, Jul 12, 2018 at 01:29:40PM -0400, Johannes Weiner wrote: > > + for (to = 0; (bo = ffs(set)); to += bo, set >>= bo) > > + tasks[to + (bo - 1)]++; > > You want to benchmark this, but since it's only 3 consecutive bits, it > might actually be faster to not use ffs() and simply test all 3 bits: > > for (to = set, bo = 0; to; to &= ~(1 << bo), bo++)
if (to & (1 << bo))
> tasks[bo]++;
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