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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 | |
| 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')
| -rw-r--r-- | arch/s390/kernel/vdso64/clock_getres.S | 5 | ||||
| -rw-r--r-- | arch/s390/kernel/vdso64/clock_gettime.S | 39 |
2 files changed, 39 insertions, 5 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 diff --git a/arch/s390/kernel/vdso64/clock_gettime.S b/arch/s390/kernel/vdso64/clock_gettime.S index 738a410b7eb2..79dbfee831ec 100644 --- a/arch/s390/kernel/vdso64/clock_gettime.S +++ b/arch/s390/kernel/vdso64/clock_gettime.S @@ -22,8 +22,10 @@ __kernel_clock_gettime: larl %r5,_vdso_data cghi %r2,CLOCK_REALTIME je 4f + cghi %r2,-2 /* CLOCK_THREAD_CPUTIME_ID for this thread */ + je 9f cghi %r2,CLOCK_MONOTONIC - jne 9f + jne 12f /* CLOCK_MONOTONIC */ ltgr %r3,%r3 @@ -42,7 +44,7 @@ __kernel_clock_gettime: alg %r0,__VDSO_WTOM_SEC(%r5) clg %r4,__VDSO_UPD_COUNT(%r5) /* check update counter */ jne 0b - larl %r5,10f + larl %r5,13f 1: clg %r1,0(%r5) jl 2f slg %r1,0(%r5) @@ -68,7 +70,7 @@ __kernel_clock_gettime: lg %r0,__VDSO_XTIME_SEC(%r5) clg %r4,__VDSO_UPD_COUNT(%r5) /* check update counter */ jne 5b - larl %r5,10f + larl %r5,13f 6: clg %r1,0(%r5) jl 7f slg %r1,0(%r5) @@ -79,11 +81,38 @@ __kernel_clock_gettime: 8: lghi %r2,0 br %r14 + /* CLOCK_THREAD_CPUTIME_ID for this thread */ +9: icm %r0,15,__VDSO_ECTG_OK(%r5) + jz 12f + ear %r2,%a4 + llilh %r4,0x0100 + sar %a4,%r4 + lghi %r4,0 + sacf 512 /* Magic ectg instruction */ + .insn ssf,0xc80100000000,__VDSO_ECTG_BASE(4),__VDSO_ECTG_USER(4),4 + sacf 0 + sar %a4,%r2 + algr %r1,%r0 /* r1 = cputime as TOD value */ + mghi %r1,1000 /* convert to nanoseconds */ + srlg %r1,%r1,12 /* r1 = cputime in nanosec */ + lgr %r4,%r1 + larl %r5,13f + srlg %r1,%r1,9 /* divide by 1000000000 */ + mlg %r0,8(%r5) + srlg %r0,%r0,11 /* r0 = tv_sec */ + stg %r0,0(%r3) + msg %r0,0(%r5) /* calculate tv_nsec */ + slgr %r4,%r0 /* r4 = tv_nsec */ + stg %r4,8(%r3) + lghi %r2,0 + br %r14 + /* Fallback to system call */ -9: lghi %r1,__NR_clock_gettime +12: lghi %r1,__NR_clock_gettime svc 0 br %r14 -10: .quad 1000000000 +13: .quad 1000000000 +14: .quad 19342813113834067 .cfi_endproc .size __kernel_clock_gettime,.-__kernel_clock_gettime |