Re: [RFC PATCH] powerpc/32: Switch VDSO to C implementation.
From: Andy Lutomirski <luto@kernel.org>
Date: 2019-10-26 13:55:44
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On Tue, Oct 22, 2019 at 6:56 AM Christophe Leroy [off-list ref] wrote:
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The performance is rather disappoiting. That's most likely all calculation in the C implementation are based on 64 bits math and converted to 32 bits at the very end. I guess C implementation should use 32 bits math like the assembly VDSO does as of today.quoted
gettimeofday: vdso: 750 nsec/call gettimeofday: vdso: 1533 nsec/callSmall improvement (3%) with the proposed change: gettimeofday: vdso: 1485 nsec/callBy inlining do_hres() I get the following: gettimeofday: vdso: 1072 nsec/call
A perf report might be informative.