From mboxrd@z Thu Jan 1 00:00:00 1970 From: robherring2@gmail.com (Rob Herring) Date: Mon, 10 Sep 2012 14:45:34 -0500 Subject: [RFC PATCH] ARM: l2x0: avoid spinlock for sync op on pl310 Message-ID: <1347306334-781-1-git-send-email-robherring2@gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org From: Rob Herring The sync op is atomic on the pl310, so a spinlock is not needed. It can be a bottleneck for code paths with register accesses, so remove it. Removing it gives a 30% improvement to pktgen throughput on highbank. A similar spinlock removal was originally done by Catalin Marinas[1], but the spinlock part was dropped in the merged version. It is unclear why other than it was not a runtime selection. As every readl/writel causes a outer_sync, the sync function is likely the most critical. [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2010-August/024514.html Signed-off-by: Rob Herring Cc: Catalin Marinas --- arch/arm/mm/cache-l2x0.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/arm/mm/cache-l2x0.c b/arch/arm/mm/cache-l2x0.c index 2a8e380..6778238 100644 --- a/arch/arm/mm/cache-l2x0.c +++ b/arch/arm/mm/cache-l2x0.c @@ -130,6 +130,11 @@ static void l2x0_cache_sync(void) raw_spin_unlock_irqrestore(&l2x0_lock, flags); } +static void pl310_cache_sync(void) +{ + cache_sync(); +} + static void __l2x0_flush_all(void) { debug_writel(0x03); @@ -335,6 +340,7 @@ void __init l2x0_init(void __iomem *base, u32 aux_val, u32 aux_mask) sync_reg_offset = L2X0_DUMMY_REG; #endif outer_cache.set_debug = pl310_set_debug; + outer_cache.sync = pl310_cache_sync; break; case L2X0_CACHE_ID_PART_L210: ways = (aux >> 13) & 0xf; -- 1.7.9.5