Messages in this thread Patch in this message | | | Date | Sat, 27 May 2006 23:48:56 +0800 | From | Wu Fengguang <> | Subject | [PATCH 07/32] readahead: insert cond_resched() calls |
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Since the VM_MAX_READAHEAD is greatly enlarged and the algorithm more complex, it becomes necessary to insert some cond_resched() calls in the read-ahead path.
If desktop users still feel audio jitters with the new read-ahead code, please try one of the following ways to get rid of it:
1) compile kernel with CONFIG_PREEMPT_VOLUNTARY/CONFIG_PREEMPT 2) reduce the read-ahead request size by running blockdev --setra 256 /dev/hda # or whatever device you are using
Signed-off-by: Wu Fengguang <wfg@mail.ustc.edu.cn> ---
This patch is recommended by Con Kolivas to improve respond time for desktop. Thanks!
fs/mpage.c | 4 +++- mm/readahead.c | 9 +++++++-- 2 files changed, 10 insertions(+), 3 deletions(-)
--- linux-2.6.17-rc4-mm3.orig/mm/readahead.c +++ linux-2.6.17-rc4-mm3/mm/readahead.c @@ -148,8 +148,10 @@ int read_cache_pages(struct address_spac continue; } ret = filler(data, page); - if (!pagevec_add(&lru_pvec, page)) + if (!pagevec_add(&lru_pvec, page)) { + cond_resched(); __pagevec_lru_add(&lru_pvec); + } if (ret) { while (!list_empty(pages)) { struct page *victim; @@ -186,8 +188,10 @@ static int read_pages(struct address_spa if (!add_to_page_cache(page, mapping, page->index, GFP_KERNEL)) { mapping->a_ops->readpage(filp, page); - if (!pagevec_add(&lru_pvec, page)) + if (!pagevec_add(&lru_pvec, page)) { + cond_resched(); __pagevec_lru_add(&lru_pvec); + } } else page_cache_release(page); } @@ -299,6 +303,7 @@ __do_page_cache_readahead(struct address continue; read_unlock_irq(&mapping->tree_lock); + cond_resched(); page = page_cache_alloc_cold(mapping); read_lock_irq(&mapping->tree_lock); if (!page) --- linux-2.6.17-rc4-mm3.orig/fs/mpage.c +++ linux-2.6.17-rc4-mm3/fs/mpage.c @@ -407,8 +407,10 @@ mpage_readpages(struct address_space *ma &last_block_in_bio, &map_bh, &first_logical_block, get_block); - if (!pagevec_add(&lru_pvec, page)) + if (!pagevec_add(&lru_pvec, page)) { + cond_resched(); __pagevec_lru_add(&lru_pvec); + } } else { page_cache_release(page); } -- - 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/
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