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| author | Alexey Dobriyan <adobriyan@gmail.com> | 2017-05-09 01:56:15 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-05-09 03:15:11 +0300 |
| commit | c311c797998c1e70eade463dd60b843da4f1a203 (patch) | |
| tree | cf20c8c1e2305c3cdc8a7e405fb69f0bc38eedb9 /arch/s390/kernel/perf_cpum_sf.c | |
| parent | 19659c59af52df22d1b85208a2c37b2d46290541 (diff) | |
| download | linux-c311c797998c1e70eade463dd60b843da4f1a203.tar.xz | |
cpumask: make "nr_cpumask_bits" unsigned
Bit searching functions accept "unsigned long" indices but
"nr_cpumask_bits" is "int" which is signed, so inevitable sign
extensions occur on x86_64. Those MOVSX are #1 MOVSX bloat by number of
uses across whole kernel.
Change "nr_cpumask_bits" to unsigned, this number can't be negative
after all. It allows to do implicit zero-extension on x86_64 without
MOVSX.
Change signed comparisons into unsigned comparisons where necessary.
Other uses looks fine because it is either argument passed to a function
or comparison is already unsigned.
Net win on allyesconfig type of kernel: ~2.8 KB (!)
add/remove: 0/0 grow/shrink: 8/725 up/down: 93/-2926 (-2833)
function old new delta
xen_exit_mmap 691 735 +44
qstat_read 426 440 +14
__cpufreq_cooling_register 1678 1687 +9
trace_rb_cpu_prepare 447 455 +8
vermagic 54 60 +6
nfp_driver_version 54 60 +6
rcu_torture_stats_print 1147 1151 +4
find_next_push_cpu 267 269 +2
xen_irq_resume 961 960 -1
...
init_vp_index 946 906 -40
od_set_powersave_bias 328 281 -47
power_cpu_exit 193 139 -54
arch_show_interrupts 3538 3484 -54
select_idle_sibling 1558 1471 -87
Total: Before=158358910, After=158356077, chg -0.00%
Same arguments apply to "nr_cpu_ids" but I haven't yet found enough
courage to delve into this issue (and proper fix may require new type
"cpu_t" which is whole separate story).
Link: http://lkml.kernel.org/r/20170309205322.GA1728@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/s390/kernel/perf_cpum_sf.c')
| -rw-r--r-- | arch/s390/kernel/perf_cpum_sf.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/s390/kernel/perf_cpum_sf.c b/arch/s390/kernel/perf_cpum_sf.c index 9a4f279d25ca..ca960d0370d5 100644 --- a/arch/s390/kernel/perf_cpum_sf.c +++ b/arch/s390/kernel/perf_cpum_sf.c @@ -823,7 +823,7 @@ static int cpumsf_pmu_event_init(struct perf_event *event) } /* Check online status of the CPU to which the event is pinned */ - if (event->cpu >= nr_cpumask_bits || + if ((unsigned int)event->cpu >= nr_cpumask_bits || (event->cpu >= 0 && !cpu_online(event->cpu))) return -ENODEV; |