Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752144AbZIBNMF (ORCPT ); Wed, 2 Sep 2009 09:12:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752122AbZIBNMD (ORCPT ); Wed, 2 Sep 2009 09:12:03 -0400 Received: from mail-bw0-f219.google.com ([209.85.218.219]:61410 "EHLO mail-bw0-f219.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752124AbZIBNMB (ORCPT ); Wed, 2 Sep 2009 09:12:01 -0400 From: "Kirill A. Shutemov" To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: Koskinen Aaro , Bityutskiy Artem , Moiseichuk Leonid , Siarhei Siamashka , "Kirill A. Shutemov" Subject: [PATCH 2/2] ARM: copy_page.S: take into account the size of the cache line Date: Wed, 2 Sep 2009 19:11:53 +0300 Message-Id: <1251907913-16261-2-git-send-email-kirill@shutemov.name> X-Mailer: git-send-email 1.6.3.4 In-Reply-To: <1251907913-16261-1-git-send-email-kirill@shutemov.name> References: <1251907913-16261-1-git-send-email-kirill@shutemov.name> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2736 Lines: 96 Optimized version of copy_page() was written with assumption that cache line size is 32 bytes. On Cortex-A8 cache line size is 64 bytes. This patch tries to generalize copy_page() to work with any cache line size if cache line size is multiple of 16 and page size is multiple of two cache line size. After this optimization we've got ~25% speedup on OMAP3(tested in userspace). There is test for kernelspace which trigger copy-on-write after fork(): #include #include #include #define BUF_SIZE (10000*4096) #define NFORK 200 int main(int argc, char **argv) { char *buf = malloc(BUF_SIZE); int i; memset(buf, 0, BUF_SIZE); for(i = 0; i < NFORK; i++) { if (fork()) { wait(NULL); } else { int j; for(j = 0; j < BUF_SIZE; j+= 4096) buf[j] = (j & 0xFF) + 1; break; } } free(buf); return 0; } Before optimization this test takes ~66 seconds, after optimization takes ~56 seconds. Signed-off-by: Siarhei Siamashka Signed-off-by: Kirill A. Shutemov --- arch/arm/lib/copy_page.S | 15 +++++++-------- 1 files changed, 7 insertions(+), 8 deletions(-) diff --git a/arch/arm/lib/copy_page.S b/arch/arm/lib/copy_page.S index 6ae04db..2107b4a 100644 --- a/arch/arm/lib/copy_page.S +++ b/arch/arm/lib/copy_page.S @@ -13,7 +13,7 @@ #include #include -#define COPY_COUNT (PAGE_SZ/64 PLD( -1 )) +#define COPY_COUNT (PAGE_SZ/(2 * L1_CACHE_BYTES) PLD( -1 )) .text .align 5 @@ -26,17 +26,16 @@ ENTRY(copy_page) stmfd sp!, {r4, lr} @ 2 PLD( pld [r1, #0] ) - PLD( pld [r1, #32] ) + PLD( pld [r1, #L1_CACHE_BYTES] ) mov r2, #COPY_COUNT @ 1 ldmia r1!, {r3, r4, ip, lr} @ 4+1 -1: PLD( pld [r1, #64] ) - PLD( pld [r1, #96] ) -2: stmia r0!, {r3, r4, ip, lr} @ 4 - ldmia r1!, {r3, r4, ip, lr} @ 4+1 - stmia r0!, {r3, r4, ip, lr} @ 4 - ldmia r1!, {r3, r4, ip, lr} @ 4+1 +1: PLD( pld [r1, #(2*L1_CACHE_BYTES)]) + PLD( pld [r1, #(3*L1_CACHE_BYTES)]) +2: + .rept (2 * (L1_CACHE_BYTES) / 16 - 1) stmia r0!, {r3, r4, ip, lr} @ 4 ldmia r1!, {r3, r4, ip, lr} @ 4 + .endr subs r2, r2, #1 @ 1 stmia r0!, {r3, r4, ip, lr} @ 4 ldmgtia r1!, {r3, r4, ip, lr} @ 4 -- 1.6.3.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/