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| author |   David Mosberger-Tang <davidm@hpl.hp.com> | 2005-04-25 13:03:16 -0700 |
|---|---|---|
| committer |   Tony Luck <tony.luck@intel.com> | 2005-04-25 13:03:16 -0700 |
| commit | 30325d17715302a60c9afdaacaafaeb056b7e880 (patch) | |
| tree | 8872d59f841a5338e04f15c1183b8fd2ad4bfbb3 /arch/ia64 | |
| parent | [IA64] Tighten up unw_unwind_to_user check (diff) | |
| download | linux-dev-30325d17715302a60c9afdaacaafaeb056b7e880.tar.xz linux-dev-30325d17715302a60c9afdaacaafaeb056b7e880.zip | |
[IA64] speed up syscall path a bit more
Recently I noticed that clearing ar.ssd/ar.csd right before srlz.d is
causing significant stalling in the syscall path. The patch below
fixes that by moving the register-writes after srlz.d. On a Madison,
this drops break-based getpid() from 241 to 226 cycles (-15 cycles).
Signed-off-by: David Mosberger-Tang <davidm@hpl.hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Diffstat (limited to 'arch/ia64')
| -rw-r--r-- | arch/ia64/kernel/entry.S | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/arch/ia64/kernel/entry.S b/arch/ia64/kernel/entry.S index 0272c010a3ba..73e23dafe8e9 100644 --- a/arch/ia64/kernel/entry.S +++ b/arch/ia64/kernel/entry.S @@ -728,12 +728,8 @@ ENTRY(ia64_leave_syscall) mov f8=f0 // clear f8 ;; ld8 r30=[r2],16 // M0|1 load cr.ifs - mov.m ar.ssd=r0 // M2 clear ar.ssd - cmp.eq p9,p0=r0,r0 // set p9 to indicate that we should restore cr.ifs - ;; ld8 r25=[r3],16 // M0|1 load ar.unat - mov.m ar.csd=r0 // M2 clear ar.csd - mov r22=r0 // clear r22 + cmp.eq p9,p0=r0,r0 // set p9 to indicate that we should restore cr.ifs ;; ld8 r26=[r2],PT(B0)-PT(AR_PFS) // M0|1 load ar.pfs (pKStk) mov r22=psr // M2 read PSR now that interrupts are disabled @@ -756,11 +752,15 @@ ENTRY(ia64_leave_syscall) mov f7=f0 // clear f7 ;; ld8.fill r12=[r2] // restore r12 (sp) + mov.m ar.ssd=r0 // M2 clear ar.ssd + mov r22=r0 // clear r22 + ld8.fill r15=[r3] // restore r15 +(pUStk) st1 [r14]=r17 addl r3=THIS_CPU(ia64_phys_stacked_size_p8),r0 ;; (pUStk) ld4 r3=[r3] // r3 = cpu_data->phys_stacked_size_p8 -(pUStk) st1 [r14]=r17 + mov.m ar.csd=r0 // M2 clear ar.csd mov b6=r18 // I0 restore b6 ;; mov r14=r0 // clear r14 |