From e03c16fb4af1dfc615a4e1f51be0d5fe5840b904 Mon Sep 17 00:00:00 2001 From: Pankaj Raghav Date: Mon, 15 Jan 2024 11:25:22 +0100 Subject: [PATCH] readahead: use ilog2 instead of a while loop in page_cache_ra_order() A while loop is used to adjust the new_order to be lower than the ra->size. ilog2 could be used to do the same instead of using a loop. ilog2 typically resolves to a bit scan reverse instruction. This is particularly useful when ra->size is smaller than the 2^new_order as it resolves in one instruction instead of looping to find the new_order. No functional changes. Link: https://lkml.kernel.org/r/20240115102523.2336742-1-kernel@pankajraghav.com Signed-off-by: Pankaj Raghav Cc: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton --- mm/readahead.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/mm/readahead.c b/mm/readahead.c index 2648ec4f04947..1e74455f908e5 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -500,10 +500,8 @@ void page_cache_ra_order(struct readahead_control *ractl, if (new_order < MAX_PAGECACHE_ORDER) { new_order += 2; - if (new_order > MAX_PAGECACHE_ORDER) - new_order = MAX_PAGECACHE_ORDER; - while ((1 << new_order) > ra->size) - new_order--; + new_order = min_t(unsigned int, MAX_PAGECACHE_ORDER, new_order); + new_order = min_t(unsigned int, new_order, ilog2(ra->size)); } filemap_invalidate_lock_shared(mapping); -- 2.30.2