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powerpc/64s: msgclr when handling doorbell exceptions from system reset

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msgsnd doorbell exceptions are cleared when the doorbell interrupt is
taken. However if a doorbell exception causes a system reset interrupt
wake from power saving state, the message is not cleared. Processing
the doorbell from the system reset interrupt requires msgclr to avoid
taking the exception again.

Testing this plus the previous wakup direct patch gives:

                                original         wakeup direct     msgclr
Different threads, same core:   315k/s           264k/s            345k/s
Different cores:                235k/s           242k/s            242k/s

Net speedup is +10% for same core, and +3% for different core.

Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Nicholas Piggin
2017-06-13 23:05:48 +10:00
committed by Michael Ellerman
parent 771d4304d0
commit a9af97aa0a
4 changed files with 38 additions and 2 deletions
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1
arch/powerpc/kernel/asm-offsets.c
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@@ -746,6 +746,7 @@ int main(void)
#endif
DEFINE(PPC_DBELL_SERVER, PPC_DBELL_SERVER);
DEFINE(PPC_DBELL_MSGTYPE, PPC_DBELL_MSGTYPE);
#ifdef CONFIG_PPC_8xx
DEFINE(VIRT_IMMR_BASE, (u64)__fix_to_virt(FIX_IMMR_BASE));

23
arch/powerpc/kernel/exceptions-64s.S
View File

@@ -1611,6 +1611,25 @@ END_FTR_SECTION_IFSET(CPU_FTR_CFAR)
bl kernel_bad_stack
b 1b
/*
* When doorbell is triggered from system reset wakeup, the message is
* not cleared, so it would fire again when EE is enabled.
*
* When coming from local_irq_enable, there may be the same problem if
* we were hard disabled.
*
* Execute msgclr to clear pending exceptions before handling it.
*/
h_doorbell_common_msgclr:
LOAD_REG_IMMEDIATE(r3, PPC_DBELL_MSGTYPE << (63-36))
PPC_MSGCLR(3)
b h_doorbell_common
doorbell_super_common_msgclr:
LOAD_REG_IMMEDIATE(r3, PPC_DBELL_MSGTYPE << (63-36))
PPC_MSGCLRP(3)
b doorbell_super_common
/*
* Called from arch_local_irq_enable when an interrupt needs
* to be resent. r3 contains 0x500, 0x900, 0xa00 or 0xe80 to indicate
@@ -1636,13 +1655,13 @@ _GLOBAL(__replay_interrupt)
beq hardware_interrupt_common
BEGIN_FTR_SECTION
cmpwi r3,0xe80
beq h_doorbell_common
beq h_doorbell_common_msgclr
cmpwi r3,0xea0
beq h_virt_irq_common
cmpwi r3,0xe60
beq hmi_exception_common
FTR_SECTION_ELSE
cmpwi r3,0xa00
beq doorbell_super_common
beq doorbell_super_common_msgclr
ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE)
blr