diff options
| author | Chris Metcalf <cmetcalf@tilera.com> | 2012-03-29 15:57:18 -0400 |
|---|---|---|
| committer | Chris Metcalf <cmetcalf@tilera.com> | 2012-04-02 12:13:29 -0400 |
| commit | 8c92ba6c327ee5089dec1e92eaa82927bee63d6d (patch) | |
| tree | 0604093dfc61953b629a0b0889b6549dc1797d6c | |
| parent | bfffe79bc29a9c4c817d5f51590961220e26db1a (diff) | |
arch/tile: add "nop" after "nap" to help GX idle power draw
This avoids the hardware istream prefetcher doing unnecessary work.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
| -rw-r--r-- | arch/tile/kernel/entry.S | 2 | ||||
| -rw-r--r-- | arch/tile/kernel/smp.c | 2 |
2 files changed, 3 insertions, 1 deletions
diff --git a/arch/tile/kernel/entry.S b/arch/tile/kernel/entry.S index 431e9ae6048..ec91568df88 100644 --- a/arch/tile/kernel/entry.S +++ b/arch/tile/kernel/entry.S @@ -85,6 +85,7 @@ STD_ENTRY(cpu_idle_on_new_stack) /* Loop forever on a nap during SMP boot. */ STD_ENTRY(smp_nap) nap + nop /* avoid provoking the icache prefetch with a jump */ j smp_nap /* we are not architecturally guaranteed not to exit nap */ jrp lr /* clue in the backtracer */ STD_ENDPROC(smp_nap) @@ -105,5 +106,6 @@ STD_ENTRY(_cpu_idle) .global _cpu_idle_nap _cpu_idle_nap: nap + nop /* avoid provoking the icache prefetch with a jump */ jrp lr STD_ENDPROC(_cpu_idle) diff --git a/arch/tile/kernel/smp.c b/arch/tile/kernel/smp.c index a44e103c5a6..7b6df8c2770 100644 --- a/arch/tile/kernel/smp.c +++ b/arch/tile/kernel/smp.c @@ -103,7 +103,7 @@ static void smp_stop_cpu_interrupt(void) set_cpu_online(smp_processor_id(), 0); arch_local_irq_disable_all(); for (;;) - asm("nap"); + asm("nap; nop"); } /* This function calls the 'stop' function on all other CPUs in the system. */ |