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| author |   Martin Schwidefsky <schwidefsky@de.ibm.com> | 2008-12-31 15:11:42 +0100 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2008-12-31 15:11:49 +0100 |
| commit | c742b31c03f37c5c499178f09f57381aa6c70131 (patch) | |
| tree | db0e95b8299d997fcb1264126bc8efe10d0ddd51 /arch/s390/kernel/vdso64/clock_getres.S | |
| parent | [PATCH] improve idle cputime accounting (diff) | |
| download | linux-dev-c742b31c03f37c5c499178f09f57381aa6c70131.tar.xz linux-dev-c742b31c03f37c5c499178f09f57381aa6c70131.zip | |
[PATCH] fast vdso implementation for CLOCK_THREAD_CPUTIME_ID
The extract cpu time instruction (ectg) instruction allows the user
process to get the current thread cputime without calling into the
kernel. The code that uses the instruction needs to switch to the
access registers mode to get access to the per-cpu info page that
contains the two base values that are needed to calculate the current
cputime from the CPU timer with the ectg instruction.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/kernel/vdso64/clock_getres.S')
| -rw-r--r-- | arch/s390/kernel/vdso64/clock_getres.S | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/s390/kernel/vdso64/clock_getres.S b/arch/s390/kernel/vdso64/clock_getres.S index 488e31a3c0e7..9ce8caafdb4e 100644 --- a/arch/s390/kernel/vdso64/clock_getres.S +++ b/arch/s390/kernel/vdso64/clock_getres.S @@ -22,7 +22,12 @@ __kernel_clock_getres: cghi %r2,CLOCK_REALTIME je 0f cghi %r2,CLOCK_MONOTONIC + je 0f + cghi %r2,-2 /* CLOCK_THREAD_CPUTIME_ID for this thread */ jne 2f + larl %r5,_vdso_data + icm %r0,15,__LC_ECTG_OK(%r5) + jz 2f 0: ltgr %r3,%r3 jz 1f /* res == NULL */ larl %r1,3f |