From 8fb870df5a1f261294b833dd807bcba3bacface6 Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Sat, 6 Oct 2007 15:12:58 -0400 Subject: [JFFS2] Trigger garbage collection when very_dirty_list size becomes excessive With huge amounts of free space, we weren't bothering to GC for while a while, and pathological numbers of obsolete nodes were accumulating, seriously affecting performance on NAND flash (OLPC trac #3978) Signed-off-by: David Woodhouse --- fs/jffs2/build.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'fs/jffs2/build.c') diff --git a/fs/jffs2/build.c b/fs/jffs2/build.c index 0ca2fff2617f..8c27c12816ba 100644 --- a/fs/jffs2/build.c +++ b/fs/jffs2/build.c @@ -285,6 +285,14 @@ static void jffs2_calc_trigger_levels(struct jffs2_sb_info *c) than actually making progress? */ c->resv_blocks_gcbad = 0;//c->resv_blocks_deletion + 2; + /* What number of 'very dirty' eraseblocks do we allow before we + trigger the GC thread even if we don't _need_ the space. When we + can't mark nodes obsolete on the medium, the old dirty nodes cause + performance problems because we have to inspect and discard them. */ + c->vdirty_blocks_gctrigger = c->resv_blocks_gcmerge; + if (jffs2_can_mark_obsolete(c)) + c->vdirty_blocks_gctrigger *= 10; + /* If there's less than this amount of dirty space, don't bother trying to GC to make more space. It'll be a fruitless task */ c->nospc_dirty_size = c->sector_size + (c->flash_size / 100); @@ -303,6 +311,8 @@ static void jffs2_calc_trigger_levels(struct jffs2_sb_info *c) c->resv_blocks_gcbad, c->resv_blocks_gcbad*c->sector_size/1024); dbg_fsbuild("Amount of dirty space required to GC: %d bytes\n", c->nospc_dirty_size); + dbg_fsbuild("Very dirty blocks before GC triggered: %d\n", + c->vdirty_blocks_gctrigger); } int jffs2_do_mount_fs(struct jffs2_sb_info *c) -- cgit v1.2.3-59-g8ed1b