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| author | Paul E. Murphy <murp@ibm.com> | 2022-10-20 17:01:01 -0500 |
|---|---|---|
| committer | Michael Knyszek <mknyszek@google.com> | 2022-11-08 18:43:38 +0000 |
| commit | 23fd10b3780e44da5fa019a7bd712729e6acfef7 (patch) | |
| tree | 6ba84947ebf450cce22bfd65ce4815c7089877c4 | |
| parent | 6109c07ec4cf2b26eba9441ad5148f8dcb8c6497 (diff) | |
| download | go-23fd10b3780e44da5fa019a7bd712729e6acfef7.tar.gz go-23fd10b3780e44da5fa019a7bd712729e6acfef7.zip | |
[release-branch.go1.19] runtime: fix usleep on linux/PPC64
The existing implementation fails to convert the remainder
microseconds to nanoseconds. This causes sysmon to consume
much more cpu, and generate lots of context switches.
We can also do a little better here to avoid division by a
constant. I used go to determine the magic numbers.
Fixes #56397
Change-Id: I2e37ec218b9027efab6db4634eed1504c0c1b3c8
Reviewed-on: https://go-review.googlesource.com/c/go/+/444735
Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>
Run-TryBot: Paul Murphy <murp@ibm.com>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/445157
| -rw-r--r-- | src/runtime/sys_linux_ppc64x.s | 23 |
1 files changed, 15 insertions, 8 deletions
diff --git a/src/runtime/sys_linux_ppc64x.s b/src/runtime/sys_linux_ppc64x.s index 6e9d8f56f1..73edf1b0f9 100644 --- a/src/runtime/sys_linux_ppc64x.s +++ b/src/runtime/sys_linux_ppc64x.s @@ -111,16 +111,23 @@ TEXT runtime·pipe2(SB),NOSPLIT|NOFRAME,$0-20 MOVW R3, errno+16(FP) RET +// func usleep(usec uint32) TEXT runtime·usleep(SB),NOSPLIT,$16-4 MOVW usec+0(FP), R3 - MOVD R3, R5 - MOVW $1000000, R4 - DIVD R4, R3 - MOVD R3, 8(R1) - MOVW $1000, R4 - MULLD R3, R4 - SUB R4, R5 - MOVD R5, 16(R1) + + // Use magic constant 0x8637bd06 and shift right 51 + // to perform usec/1000000. + ORIS $0x8637, R0, R4 // Note, R0 always contains 0 here. + OR $0xbd06, R4, R4 + MULLD R3, R4, R4 // Convert usec to S. + SRD $51, R4, R4 + MOVD R4, 8(R1) // Store to tv_sec + + MOVD $1000000, R5 + MULLW R4, R5, R5 // Convert tv_sec back into uS + SUB R5, R3, R5 // Compute remainder uS. + MULLD $1000, R5, R5 // Convert to nsec + MOVD R5, 16(R1) // Store to tv_nsec // nanosleep(&ts, 0) ADD $8, R1, R3 |