Hi,

Here is a patch that prunes unused, clean inodes from the icache
faster.  I have previously checked out cleaning the unused dirty
icache entries from the the same place in kswapd but did not find
it to be much a win.

This code does the following.  It factors prune_icache to use,  
prune_unused_icache to actually prune the list.   This makes it
simple to add a shrink_unused_icache_memory routine which gets
plugged into the kswapd loop.  The result is the icache is kept 
smaller.

fast_prune.diff
-----
--- 2.4.4-pre7/include/linux/dcache.h   Thu Apr 26 12:57:47 2001
+++ linux/include/linux/dcache.h        Fri Apr 27 18:17:20 2001
@@ -176,6 +176,7 @@
 
 /* icache memory management (defined in linux/fs/inode.c) */
 extern void shrink_icache_memory(int, int);
+extern void shrink_unused_icache_memory(int);
 extern void prune_icache(int);
 
 /* only used at mount-time */
--- 2.4.4-pre7/mm/vmscan.c      Fri Apr 27 11:36:04 2001
+++ linux/mm/vmscan.c   Fri Apr 27 18:33:07 2001
@@ -953,6 +953,11 @@
                 */
                refill_inactive_scan(DEF_PRIORITY, 0);
 
+               /* 
+                * Free unused inodes.
+                */
+               shrink_unused_icache_memory(GFP_KSWAPD);
+
                /* Once a second, recalculate some VM stats. */
                if (time_after(jiffies, recalc + HZ)) {
                        recalc = jiffies;
--- 2.4.4-pre7/fs/inode.c       Thu Apr 26 12:49:33 2001
+++ linux/fs/inode.c    Fri Apr 27 18:54:25 2001
@@ -540,16 +540,16 @@
         !inode_has_buffers(inode))
 #define INODE(entry)   (list_entry(entry, struct inode, i_list))
 
-void prune_icache(int goal)
+/*
+ * Called with inode lock held, returns with it released.
+ */
+int prune_unused_icache(int goal)
 {
        LIST_HEAD(list);
        struct list_head *entry, *freeable = &list;
-       int count = 0, synced = 0;
+       int count = 0;
        struct inode * inode;
 
-       spin_lock(&inode_lock);
-
-free_unused:
        entry = inode_unused.prev;
        while (entry != &inode_unused)
        {
@@ -577,19 +577,27 @@
 
        dispose_list(freeable);
 
+       return count;
+}
+
+/*
+ * A goal of zero frees everything
+ */
+void prune_icache(int goal)
+{
+       spin_lock(&inode_lock);
+       goal -= prune_unused_icache(goal);
+
        /* 
         * If we freed enough clean inodes, avoid writing 
-        * dirty ones. Also giveup if we already tried to
-        * sync dirty inodes.
+        * dirty ones.
         */
-       if (!goal || synced)
+       if (!goal)
                return;
        
-       synced = 1;
-
        spin_lock(&inode_lock);
        try_to_sync_unused_inodes();
-       goto free_unused;
+       prune_unused_icache(goal);
 }
 
 void shrink_icache_memory(int priority, int gfp_mask)
@@ -611,6 +619,20 @@
 
        prune_icache(count);
        kmem_cache_shrink(inode_cachep);
+}
+
+void shrink_unused_icache_memory(int gfp_mask)
+{
+       /*
+        * Nasty deadlock avoidance..
+        */
+       if (!(gfp_mask & __GFP_IO))
+               return;
+
+       if (spin_trylock(&inode_lock)) {
+               prune_unused_icache(0);
+               kmem_cache_shrink(inode_cachep);
+       }
 }
 
 /*
-----

Comments?

Ed Tomlinson <[EMAIL PROTECTED]>
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