Patchwork JFFS2 very slow when erasing

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Submitter Joakim Tjernlund
Date Oct. 7, 2010, 7:49 a.m.
Message ID <OF2426448C.2DD5559B-ONC12577B5.002AC992-C12577B5.002B0177@transmode.se>
Download mbox | patch
Permalink /patch/67001/
State New
Headers show

Comments

Joakim Tjernlund - Oct. 7, 2010, 7:49 a.m.
> With 2.6.35 JFFS2 takes a very long time cp files while it erases:
>  cp big_file test
>  rm test
>  cp big_file test
> The last cp op. takes several times longer because JFFS2 is erasing.
> Revering the patches I helped out with make JFFS2 go fast again:
>   jffs2: Stop triggering block erases from jffs2_write_super()
>   jffs2: Rename jffs2_erase_pending_trigger() to jffs2_dirty_trigger()
>   jffs2: Use jffs2_garbage_collect_trigger() to trigger pending erases
>   jffs2: Require jffs2_garbage_collect_trigger() to be called with lock held
>   jffs2: Wake GC thread when there are blocks to be erased
>   jffs2: Erase pending blocks in GC pass, avoid invalid -EIO return
>
> The final patches were somewhat different than the ones I originally wrote
> and I THINK those didn't make JFFS2 go this slow.
>
> I suspect there is a locking problem somewhere.

Commenting out this makes JFFS2 fast again:
Seems to me that jffs2_garbage_collect_pass() is trying too much.
David?

      Jocke

Patch

diff --git a/fs/jffs2/gc.c b/fs/jffs2/gc.c
index f5e96bd..bce3a30 100644
--- a/fs/jffs2/gc.c
+++ b/fs/jffs2/gc.c
@@ -213,7 +213,7 @@  int jffs2_garbage_collect_pass(struct jffs2_sb_info *c)
 		mutex_unlock(&c->alloc_sem);
 		return ret;
 	}
-
+#if 0
 	/* If there are any blocks which need erasing, erase them now */
 	if (!list_empty(&c->erase_complete_list) ||
 	    !list_empty(&c->erase_pending_list)) {
@@ -226,7 +226,7 @@  int jffs2_garbage_collect_pass(struct jffs2_sb_info *c)
 		D1(printk(KERN_DEBUG "No progress from erasing blocks; doing GC anyway\n"));
 		spin_lock(&c->erase_completion_lock);
 	}
-
+#endif
 	/* First, work out which block we're garbage-collecting */
 	jeb = c->gcblock;