@@ -27,20 +27,50 @@
* x1 - src
*/
ENTRY(copy_page)
- /* Assume cache line size is 64 bytes. */
- prfm pldl1strm, [x1, #64]
-1: ldp x2, x3, [x1]
+ ldp x2, x3, [x1]
ldp x4, x5, [x1, #16]
ldp x6, x7, [x1, #32]
ldp x8, x9, [x1, #48]
- add x1, x1, #64
- prfm pldl1strm, [x1, #64]
+ ldp x10, x11, [x1, #64]
+ ldp x12, x13, [x1, #80]
+ ldp x14, x15, [x1, #96]
+ ldp x16, x17, [x1, #112]
+
+ mov x18, #(PAGE_SIZE - 128)
+ add x1, x1, #128
+1:
+ subs x18, x18, #128
+
stnp x2, x3, [x0]
+ ldp x2, x3, [x1]
stnp x4, x5, [x0, #16]
+ ldp x4, x5, [x1, #16]
stnp x6, x7, [x0, #32]
+ ldp x6, x7, [x1, #32]
stnp x8, x9, [x0, #48]
- add x0, x0, #64
- tst x1, #(PAGE_SIZE - 1)
- b.ne 1b
+ ldp x8, x9, [x1, #48]
+ stnp x10, x11, [x0, #64]
+ ldp x10, x11, [x1, #64]
+ stnp x12, x13, [x0, #80]
+ ldp x12, x13, [x1, #80]
+ stnp x14, x15, [x0, #96]
+ ldp x14, x15, [x1, #96]
+ stnp x16, x17, [x0, #112]
+ ldp x16, x17, [x1, #112]
+
+ add x0, x0, #128
+ add x1, x1, #128
+
+ b.gt 1b
+
+ stnp x2, x3, [x0]
+ stnp x4, x5, [x0, #16]
+ stnp x6, x7, [x0, #32]
+ stnp x8, x9, [x0, #48]
+ stnp x10, x11, [x0, #64]
+ stnp x12, x13, [x0, #80]
+ stnp x14, x15, [x0, #96]
+ stnp x16, x17, [x0, #112]
+
ret
ENDPROC(copy_page)
We want to avoid lots of different copy_page implementations, settling for something that is "good enough" everywhere and hopefully easy to understand and maintain whilst we're at it. This patch reworks our copy_page implementation based on discussions with Cavium on the list and benchmarking on Cortex-A processors so that: - The loop is unrolled to copy 128 bytes per iteration - The reads are offset so that we read from the next 128-byte block in the same iteration that we store the previous block - Explicit prefetch instructions are removed for now, since they hurt performance on CPUs with hardware prefetching - The loop exit condition is calculated at the start of the loop Signed-off-by: Will Deacon <will.deacon@arm.com> --- arch/arm64/lib/copy_page.S | 46 ++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 38 insertions(+), 8 deletions(-) -- 2.1.4 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel