Re: [PATCHv7 18/33] lib/vdso: Add unlikely() hint into vdso_read_begin()
From: Andrei Vagin <hidden>
Date: 2019-10-24 06:13:18
Also in:
lkml
On Wed, Oct 16, 2019 at 12:24:14PM +0100, Vincenzo Frascino wrote:
On 10/11/19 2:23 AM, Dmitry Safonov wrote:quoted
From: Andrei Vagin <redacted> Place the branch with no concurrent write before contended case. Performance numbers for Intel(R) Core(TM) i5-6300U CPU @ 2.40GHz (more clock_gettime() cycles - the better): | before | after ----------------------------------- | 150252214 | 153242367 | 150301112 | 153324800 | 150392773 | 153125401 | 150373957 | 153399355 | 150303157 | 153489417 | 150365237 | 153494270 ----------------------------------- avg | 150331408 | 153345935 diff % | 2 | 0 ----------------------------------- stdev % | 0.3 | 0.1 Signed-off-by: Andrei Vagin <redacted> Co-developed-by: Dmitry Safonov <redacted> Signed-off-by: Dmitry Safonov <redacted>Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Hello Vincenzo, Could you test the attached patch on aarch64? On x86, it gives about 9% performance improvement for CLOCK_MONOTONIC and CLOCK_BOOTTIME. Here is my test: https://github.com/avagin/vdso-perf It is calling clock_gettime() in a loop for three seconds and then reports a number of iterations. Thanks, Andrei
Attachments
- 0001-lib-vdso-make-do_hres-and-do_coarse-as-__always_inli.patch [text/plain] 2208 bytes · preview