| Message ID | 20170611235835.7400-7-npiggin@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On Mon, Jun 12, 2017 at 09:58:27AM +1000, Nicholas Piggin wrote: > The __replay_interrupt code is branched to with bl, but the caller is > returned to directly with rfid from the interrupt. > > Instead return to a return stub that returns to the caller with blr, > which should do better with the return predictor. > > Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com> > --- > arch/powerpc/kernel/exceptions-64s.S | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S > index a04ee0d7f88e..d55201625ea3 100644 > --- a/arch/powerpc/kernel/exceptions-64s.S > +++ b/arch/powerpc/kernel/exceptions-64s.S > @@ -1586,7 +1586,7 @@ _GLOBAL(__replay_interrupt) > * we don't give a damn about, so we don't bother storing them. > */ > mfmsr r12 > - mflr r11 > + LOAD_REG_ADDR(r11, __replay_interrupt_return) > mfcr r9 > ori r12,r12,MSR_EE > cmpwi r3,0x900 > @@ -1604,4 +1604,5 @@ FTR_SECTION_ELSE > cmpwi r3,0xa00 > beq doorbell_super_common_msgclr > ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE) > +__replay_interrupt_return: > blr > -- > 2.11.0 >
Nicholas Piggin <npiggin@gmail.com> writes: > The __replay_interrupt code is branched to with bl, but the caller is > returned to directly with rfid from the interrupt. > > Instead return to a return stub that returns to the caller with blr, > which should do better with the return predictor. > > Signed-off-by: Nicholas Piggin <npiggin@gmail.com> > --- > arch/powerpc/kernel/exceptions-64s.S | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S > index a04ee0d7f88e..d55201625ea3 100644 > --- a/arch/powerpc/kernel/exceptions-64s.S > +++ b/arch/powerpc/kernel/exceptions-64s.S > @@ -1586,7 +1586,7 @@ _GLOBAL(__replay_interrupt) > * we don't give a damn about, so we don't bother storing them. > */ > mfmsr r12 > - mflr r11 > + LOAD_REG_ADDR(r11, __replay_interrupt_return) Can you make it a local label, to make it clear nothing outside the file returns to there, and to not clutter the symbol map? cheers
On Tue, 13 Jun 2017 19:51:19 +1000 Michael Ellerman <mpe@ellerman.id.au> wrote: > Nicholas Piggin <npiggin@gmail.com> writes: > > > The __replay_interrupt code is branched to with bl, but the caller is > > returned to directly with rfid from the interrupt. > > > > Instead return to a return stub that returns to the caller with blr, > > which should do better with the return predictor. > > > > Signed-off-by: Nicholas Piggin <npiggin@gmail.com> > > --- > > arch/powerpc/kernel/exceptions-64s.S | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S > > index a04ee0d7f88e..d55201625ea3 100644 > > --- a/arch/powerpc/kernel/exceptions-64s.S > > +++ b/arch/powerpc/kernel/exceptions-64s.S > > @@ -1586,7 +1586,7 @@ _GLOBAL(__replay_interrupt) > > * we don't give a damn about, so we don't bother storing them. > > */ > > mfmsr r12 > > - mflr r11 > > + LOAD_REG_ADDR(r11, __replay_interrupt_return) > > Can you make it a local label, to make it clear nothing outside the file > returns to there, and to not clutter the symbol map? I can do that. Interrupt returns will now get significantly attributed to this guy in profiles (and you can see it on some sleep/wake workloads). __replay_interrupt is probably better than arch_local_irq_restore, I guess. Thanks, Nick
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index a04ee0d7f88e..d55201625ea3 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -1586,7 +1586,7 @@ _GLOBAL(__replay_interrupt) * we don't give a damn about, so we don't bother storing them. */ mfmsr r12 - mflr r11 + LOAD_REG_ADDR(r11, __replay_interrupt_return) mfcr r9 ori r12,r12,MSR_EE cmpwi r3,0x900 @@ -1604,4 +1604,5 @@ FTR_SECTION_ELSE cmpwi r3,0xa00 beq doorbell_super_common_msgclr ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE) +__replay_interrupt_return: blr
The __replay_interrupt code is branched to with bl, but the caller is returned to directly with rfid from the interrupt. Instead return to a return stub that returns to the caller with blr, which should do better with the return predictor. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- arch/powerpc/kernel/exceptions-64s.S | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)