use pdflush for unused inode writeback
PATCH 1/1 use pdflush for unused inode writeback
This is pdflush's first application! The writeback of the unused inodes list by keventd is removed, and a pdflush thread is dispatched instead.
There is a need for exclusion - to prevent all the pdflush threads from working against the same request queue. This is implemented locally. And this is a problem, because other pdflush threads can be dispatched to writeback other filesystem objects, and they don't know that there's already a pdflush thread working that request queue.
So moving the exclusion into the request queue itself is on my things-to-do-list. But the code as-is works OK - under a `dbench 100' load the number of pdflush instances can grow as high as four or five. Some fine tuning is needed...
Patch is against 2.5.8-pre3+ratcache+readahead+pageprivate+pdflush
fs/inode.c renamed from fs/inode.c~dallocbase-45-pdflush_inodes +11 -7
@@ -433,7 +433,7 @@ void sync_inodes(void) } } -static void try_to_sync_unused_inodes (void * arg) +static void try_to_sync_unused_inodes (unsigned long pexclusive) {struct super_block * sb;int nr_inodes = inodes_stat.nr_unused;
@@ -450,10 +450,9 @@ static void try_to_sync_unused_inodes(vo }spin_unlock (&sb_lock);spin_unlock (&inode_lock); +clear_bit (0 , (unsigned long *)pexclusive); } -static struct tq_struct unused_inodes_flush_task; -/** * write_inode_now - write an inode to disk * @inode: inode to write to disk
@@ -746,8 +745,15 @@ void prune_icache(int goal)* from here or we're either synchronously dogslow * or we deadlock with oom. */ -if (goal) -schedule_task (&unused_inodes_flush_task); +if (goal) { +static unsigned long exclusive; + +if (!test_and_set_bit (0 , &exclusive)) { +if (pdflush_operation (try_to_sync_unused_inodes, + (unsigned long )&exclusive)) +clear_bit (0 , &exclusive); + } + } }/* * This is called from kswapd when we think we need some
@@ -1173,8 +1179,6 @@ void __init inode_init(unsigned long mem NULL);if (!inode_cachep)panic ("cannot create inode slab cache" ); - - unused_inodes_flush_task.routine = try_to_sync_unused_inodes; }static inline void do_atime_update (struct inode *inode)
-