From cd97d9e8b5aa45a7f867a10e99f1d6ce0a5deb8b Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Thu, 8 Apr 2021 15:30:29 +0000 Subject: [PATCH] powerpc/mem: Optimise flush_dcache_icache_hugepage() flush_dcache_icache_hugepage() is a static function, with only one caller. That caller calls it when PageCompound() is true, so bugging on !PageCompound() is useless if we can trust the compiler a little. Remove the BUG_ON(!PageCompound()). The number of elements of a page won't change over time, but GCC doesn't know about it, so it gets the value at every iteration. To avoid that, call compound_nr() outside the loop and save it in a local variable. Whether the page is a HIGHMEM page or not doesn't change over time. But GCC doesn't know it so it does the test on every iteration. Do the test outside the loop. When the page is not a HIGHMEM page, page_address() will fallback on lowmem_page_address(), so call lowmem_page_address() directly and don't suffer the call to page_address() on every iteration. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/ab03712b70105fccfceef095aa03007de9295a40.1617895813.git.christophe.leroy@csgroup.eu --- arch/powerpc/mm/cacheflush.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/arch/powerpc/mm/cacheflush.c b/arch/powerpc/mm/cacheflush.c index 811045c..3268a3e 100644 --- a/arch/powerpc/mm/cacheflush.c +++ b/arch/powerpc/mm/cacheflush.c @@ -162,14 +162,14 @@ static void __flush_dcache_icache(void *p) static void flush_dcache_icache_hugepage(struct page *page) { int i; + int nr = compound_nr(page); void *start; - BUG_ON(!PageCompound(page)); - - for (i = 0; i < compound_nr(page); i++) { - if (!PageHighMem(page)) { - __flush_dcache_icache(page_address(page+i)); - } else { + if (!PageHighMem(page)) { + for (i = 0; i < nr; i++) + __flush_dcache_icache(lowmem_page_address(page + i)); + } else { + for (i = 0; i < nr; i++) { start = kmap_atomic(page+i); __flush_dcache_icache(start); kunmap_atomic(start); -- 2.7.4