[dm-devel] [PATCH 1/2] Revert "Revert "math64: New div64_u64_rem helper""
Stanislaw Gruszka
sgruszka at redhat.com
Tue Aug 20 07:00:46 UTC 2013
On Fri, Aug 09, 2013 at 03:56:03PM -0400, Mike Snitzer wrote:
> This reverts commit f3002134158092178be81339ec5a22ff80e6c308.
>
> div64_u64_rem was removed because there were no other users.
>
> But Device Mapper's I/O statistics support has a need for
> div64_u64_rem; reintroduce this helper.
This slows down div64_u64 operation, especially on 32-bit systems.
Since dm statistic code is possibly not performance critical
perhaps you could use something like below instead to calculate
remainder:
res = div64_u64(a, b);
rem = a - b*res;
Stanislaw
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