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[IA64] VIRT_CPU_ACCOUNTING (accurate cpu time accounting)

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This patch implements VIRT_CPU_ACCOUNTING for ia64,
which enable us to use more accurate cpu time accounting.

The VIRT_CPU_ACCOUNTING is an item of kernel config, which s390
and powerpc arch have.  By turning this config on, these archs
change the mechanism of cpu time accounting from tick-sampling
based one to state-transition based one.

The state-transition based accounting is done by checking time
(cycle counter in processor) at every state-transition point,
such as entrance/exit of kernel, interrupt, softirq etc.
The difference between point to point is the actual time consumed
during in the state. There is no doubt about that this value is
more accurate than that of tick-sampling based accounting.

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This commit is contained in:
Hidetoshi Seto
2008-01-29 14:27:30 +09:00
committed by Tony Luck
parent 5d9c4a7de6
commit b64f34cdfe
12 changed files with 432 additions and 1 deletions
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26
arch/ia64/kernel/fsys.S
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@@ -660,7 +660,11 @@ GLOBAL_ENTRY(fsys_bubble_down)
nop.i 0
;;
mov ar.rsc=0 // M2 set enforced lazy mode, pl 0, LE, loadrs=0
#ifdef CONFIG_VIRT_CPU_ACCOUNTING
mov.m r30=ar.itc // M get cycle for accounting
#else
nop.m 0
#endif
nop.i 0
;;
mov r23=ar.bspstore // M2 (12 cyc) save ar.bspstore
@@ -682,6 +686,28 @@ GLOBAL_ENTRY(fsys_bubble_down)
cmp.ne pKStk,pUStk=r0,r0 // A set pKStk <- 0, pUStk <- 1
br.call.sptk.many b7=ia64_syscall_setup // B
;;
#ifdef CONFIG_VIRT_CPU_ACCOUNTING
// mov.m r30=ar.itc is called in advance
add r16=TI_AC_STAMP+IA64_TASK_SIZE,r2
add r17=TI_AC_LEAVE+IA64_TASK_SIZE,r2
;;
ld8 r18=[r16],TI_AC_STIME-TI_AC_STAMP // time at last check in kernel
ld8 r19=[r17],TI_AC_UTIME-TI_AC_LEAVE // time at leave kernel
;;
ld8 r20=[r16],TI_AC_STAMP-TI_AC_STIME // cumulated stime
ld8 r21=[r17] // cumulated utime
sub r22=r19,r18 // stime before leave kernel
;;
st8 [r16]=r30,TI_AC_STIME-TI_AC_STAMP // update stamp
sub r18=r30,r19 // elapsed time in user mode
;;
add r20=r20,r22 // sum stime
add r21=r21,r18 // sum utime
;;
st8 [r16]=r20 // update stime
st8 [r17]=r21 // update utime
;;
#endif
mov ar.rsc=0x3 // M2 set eager mode, pl 0, LE, loadrs=0
mov rp=r14 // I0 set the real return addr
and r3=_TIF_SYSCALL_TRACEAUDIT,r3 // A