1021.lowlatency.patch

sm86xx内核源包括补丁（ GPL ）的

--- linuxmips-2.4.30.ref/fs/jbd/checkpoint.c	2003-01-11 09:53:17.000000000 -0800
+++ linuxmips-2.4.30/fs/jbd/checkpoint.c	2005-07-22 09:36:02.000000000 -0700
@@ -431,7 +431,11 @@
 {
 	transaction_t *transaction, *last_transaction, *next_transaction;
 	int ret = 0;
+	int ll_retries = 4;		/* lowlatency addition */
 
+restart:
+	if (ll_retries-- == 0)
+		goto out;
 	transaction = journal->j_checkpoint_transactions;
 	if (transaction == 0)
 		goto out;
@@ -451,6 +455,12 @@
 				jh = next_jh;
 				next_jh = jh->b_cpnext;
 				ret += __try_to_free_cp_buf(jh);
+				if (conditional_schedule_needed()) {
+					spin_unlock(&journal_datalist_lock);
+					unconditional_schedule();
+					spin_lock(&journal_datalist_lock);
+					goto restart;
+				}
 			} while (jh != last_jh);
 		}
 	} while (transaction != last_transaction);
diff -Naur --exclude=CVS --exclude='*.o' --exclude='*.a' --exclude='*.so' --exclude='*.elf' --exclude=System.map --exclude=Makefile.d --exclude='*log' --exclude='*log2' --exclude='*~' --exclude='.*~' --exclude='.#*' --exclude='*.bak' --exclude='*.orig' --exclude='*.rej' --exclude='core.[0-9]*' --exclude=.depend --exclude='.*.o.flags' --exclude='*.gz' --exclude=.depend --exclude='.*.o.flags' --exclude='*.gz' --exclude=vmlinux --exclude=vmlinux.bin --exclude=yamon-02.06-SIGMADESIGNS-01_el.bin linuxmips-2.4.30.ref/fs/jbd/commit.c linuxmips-2.4.30/fs/jbd/commit.c
--- linuxmips-2.4.30.ref/fs/jbd/commit.c	2005-04-05 12:09:57.000000000 -0700
+++ linuxmips-2.4.30/fs/jbd/commit.c	2005-07-22 09:36:02.000000000 -0700
@@ -280,8 +280,7 @@
 		journal_brelse_array(wbuf, bufs);
 		lock_journal(journal);
 		spin_lock(&journal_datalist_lock);
-		if (bufs)
-			goto write_out_data_locked;
+		goto write_out_data_locked;
 	}
 
 	/*
@@ -317,6 +316,15 @@
 	 */
 	while ((jh = commit_transaction->t_async_datalist)) {
 		struct buffer_head *bh = jh2bh(jh);
+
+		if (conditional_schedule_needed()) {
+			spin_unlock(&journal_datalist_lock);
+			unlock_journal(journal);
+			unconditional_schedule();
+			lock_journal(journal);
+			spin_lock(&journal_datalist_lock);
+			continue;	/* List may have changed */
+		}
 		if (__buffer_state(bh, Freed)) {
 			BUFFER_TRACE(bh, "Cleaning freed buffer");
 			clear_bit(BH_Freed, &bh->b_state);
@@ -347,6 +355,16 @@
 			if (bh->b_list != BUF_CLEAN)
 				refile_buffer(bh);
 			__brelse(bh);
+				if (conditional_schedule_needed()) {
+					if (commit_transaction->t_sync_datalist)
+						commit_transaction->t_sync_datalist =
+							next_jh;
+					if (bufs)
+						break;
+					spin_unlock(&journal_datalist_lock);
+					unconditional_schedule();
+					goto write_out_data;
+				}
 		}
 	}
 	spin_unlock(&journal_datalist_lock);
@@ -536,6 +554,8 @@
  wait_for_iobuf:
 	while (commit_transaction->t_iobuf_list != NULL) {
 		struct buffer_head *bh;
+
+		conditional_schedule();
 		jh = commit_transaction->t_iobuf_list->b_tprev;
 		bh = jh2bh(jh);
 		if (buffer_locked(bh)) {
@@ -695,6 +715,8 @@
 		struct buffer_head *bh;
 		int was_freed = 0;
 		
+		conditional_schedule();		/* journal is locked */
+
 		jh = commit_transaction->t_forget;
 		J_ASSERT_JH(jh,	jh->b_transaction == commit_transaction ||
 			jh->b_transaction == journal->j_running_transaction);
diff -Naur --exclude=CVS --exclude='*.o' --exclude='*.a' --exclude='*.so' --exclude='*.elf' --exclude=System.map --exclude=Makefile.d --exclude='*log' --exclude='*log2' --exclude='*~' --exclude='.*~' --exclude='.#*' --exclude='*.bak' --exclude='*.orig' --exclude='*.rej' --exclude='core.[0-9]*' --exclude=.depend --exclude='.*.o.flags' --exclude='*.gz' --exclude=.depend --exclude='.*.o.flags' --exclude='*.gz' --exclude=vmlinux --exclude=vmlinux.bin --exclude=yamon-02.06-SIGMADESIGNS-01_el.bin linuxmips-2.4.30.ref/fs/proc/array.c linuxmips-2.4.30/fs/proc/array.c
--- linuxmips-2.4.30.ref/fs/proc/array.c	2004-11-29 09:47:18.000000000 -0800
+++ linuxmips-2.4.30/fs/proc/array.c	2005-07-22 09:36:02.000000000 -0700
@@ -422,9 +422,11 @@
 	if (end > PMD_SIZE)
 		end = PMD_SIZE;
 	do {
-		pte_t page = *pte;
+		pte_t page;
 		struct page *ptpage;
 
+		conditional_schedule();		/* For `top' and `ps' */
+		page = *pte;
 		address += PAGE_SIZE;
 		pte++;
 		if (pte_none(page))
diff -Naur --exclude=CVS --exclude='*.o' --exclude='*.a' --exclude='*.so' --exclude='*.elf' --exclude=System.map --exclude=Makefile.d --exclude='*log' --exclude='*log2' --exclude='*~' --exclude='.*~' --exclude='.#*' --exclude='*.bak' --exclude='*.orig' --exclude='*.rej' --exclude='core.[0-9]*' --exclude=.depend --exclude='.*.o.flags' --exclude='*.gz' --exclude=.depend --exclude='.*.o.flags' --exclude='*.gz' --exclude=vmlinux --exclude=vmlinux.bin --exclude=yamon-02.06-SIGMADESIGNS-01_el.bin linuxmips-2.4.30.ref/fs/proc/generic.c linuxmips-2.4.30/fs/proc/generic.c
--- linuxmips-2.4.30.ref/fs/proc/generic.c	2004-11-29 09:47:18.000000000 -0800
+++ linuxmips-2.4.30/fs/proc/generic.c	2005-07-22 09:36:02.000000000 -0700
@@ -101,6 +101,8 @@
 				retval = n;
 			break;
 		}
+
+		conditional_schedule();		/* Some /proc files are large */
 		
 		/* This is a hack to allow mangling of file pos independent
  		 * of actual bytes read.  Simply place the data at page,
diff -Naur --exclude=CVS --exclude='*.o' --exclude='*.a' --exclude='*.so' --exclude='*.elf' --exclude=System.map --exclude=Makefile.d --exclude='*log' --exclude='*log2' --exclude='*~' --exclude='.*~' --exclude='.#*' --exclude='*.bak' --exclude='*.orig' --exclude='*.rej' --exclude='core.[0-9]*' --exclude=.depend --exclude='.*.o.flags' --exclude='*.gz' --exclude=.depend --exclude='.*.o.flags' --exclude='*.gz' --exclude=vmlinux --exclude=vmlinux.bin --exclude=yamon-02.06-SIGMADESIGNS-01_el.bin linuxmips-2.4.30.ref/fs/reiserfs/buffer2.c linuxmips-2.4.30/fs/reiserfs/buffer2.c
--- linuxmips-2.4.30.ref/fs/reiserfs/buffer2.c	2003-08-13 10:19:25.000000000 -0700
+++ linuxmips-2.4.30/fs/reiserfs/buffer2.c	2005-07-22 09:36:02.000000000 -0700
@@ -54,6 +54,7 @@
     PROC_EXP( unsigned int ctx_switches = kstat.context_swtch );
 
     result = bread (super -> s_dev, n_block, n_size);
+    conditional_schedule();
     PROC_INFO_INC( super, breads );
     PROC_EXP( if( kstat.context_swtch != ctx_switches ) 
 	      PROC_INFO_INC( super, bread_miss ) );
diff -Naur --exclude=CVS --exclude='*.o' --exclude='*.a' --exclude='*.so' --exclude='*.elf' --exclude=System.map --exclude=Makefile.d --exclude='*log' --exclude='*log2' --exclude='*~' --exclude='.*~' --exclude='.#*' --exclude='*.bak' --exclude='*.orig' --exclude='*.rej' --exclude='core.[0-9]*' --exclude=.depend --exclude='.*.o.flags' --exclude='*.gz' --exclude=.depend --exclude='.*.o.flags' --exclude='*.gz' --exclude=vmlinux --exclude=vmlinux.bin --exclude=yamon-02.06-SIGMADESIGNS-01_el.bin linuxmips-2.4.30.ref/fs/reiserfs/journal.c linuxmips-2.4.30/fs/reiserfs/journal.c
--- linuxmips-2.4.30.ref/fs/reiserfs/journal.c	2004-08-14 11:39:01.000000000 -0700
+++ linuxmips-2.4.30/fs/reiserfs/journal.c	2005-07-22 09:36:02.000000000 -0700
@@ -577,6 +577,7 @@
 /* lock the current transaction */
 inline static void lock_journal(struct super_block *p_s_sb) {
   PROC_INFO_INC( p_s_sb, journal.lock_journal );
+  conditional_schedule();
   while(atomic_read(&(SB_JOURNAL(p_s_sb)->j_wlock)) > 0) {
     PROC_INFO_INC( p_s_sb, journal.lock_journal_wait );
     sleep_on(&(SB_JOURNAL(p_s_sb)->j_wait)) ;
@@ -707,6 +708,7 @@
 	mark_buffer_dirty(tbh) ;
       }
       ll_rw_block(WRITE, 1, &tbh) ;
+      conditional_schedule();
       count++ ;
       put_bh(tbh) ; /* once for our get_hash */
     } 
@@ -836,6 +838,7 @@
     set_bit(BH_Dirty, &(SB_JOURNAL(p_s_sb)->j_header_bh->b_state)) ;
     ll_rw_block(WRITE, 1, &(SB_JOURNAL(p_s_sb)->j_header_bh)) ;
     wait_on_buffer((SB_JOURNAL(p_s_sb)->j_header_bh)) ; 
+    conditional_schedule();
     if (!buffer_uptodate(SB_JOURNAL(p_s_sb)->j_header_bh)) {
       reiserfs_warning( p_s_sb, "reiserfs: journal-837: IO error during journal replay\n" );
       return -EIO ;
@@ -2363,6 +2366,7 @@
 }
 
 int journal_begin(struct reiserfs_transaction_handle *th, struct super_block  * p_s_sb, unsigned long nblocks) {
+  conditional_schedule();
   return do_journal_begin_r(th, p_s_sb, nblocks, 0) ;
 }
 
@@ -2503,6 +2507,7 @@
 }
 
 int journal_end(struct reiserfs_transaction_handle *th, struct super_block *p_s_sb, unsigned long nblocks) {
+  conditional_schedule();
   return do_journal_end(th, p_s_sb, nblocks, 0) ;
 }
 
@@ -2974,6 +2979,7 @@
       RFALSE( buffer_locked(bh) && cur_tb != NULL,
 	      "waiting while do_balance was running\n") ;
       wait_on_buffer(bh) ;
+      conditional_schedule();
     }
     PROC_INFO_INC( p_s_sb, journal.prepare_retry );
     retry_count++ ;
@@ -3148,6 +3154,7 @@
     /* copy all the real blocks into log area.  dirty log blocks */
     if (test_bit(BH_JDirty, &cn->bh->b_state)) {
       struct buffer_head *tmp_bh ;
+      conditional_schedule();
       tmp_bh =  journal_getblk(p_s_sb, SB_ONDISK_JOURNAL_1st_BLOCK(p_s_sb) + 
 		       ((cur_write_start + jindex) % SB_ONDISK_JOURNAL_SIZE(p_s_sb))) ;
       mark_buffer_uptodate(tmp_bh, 1) ;
diff -Naur --exclude=CVS --exclude='*.o' --exclude='*.a' --exclude='*.so' --exclude='*.elf' --exclude=System.map --exclude=Makefile.d --exclude='*log' --exclude='*log2' --exclude='*~' --exclude='.*~' --exclude='.#*' --exclude='*.bak' --exclude='*.orig' --exclude='*.rej' --exclude='core.[0-9]*' --exclude=.depend --exclude='.*.o.flags' --exclude='*.gz' --exclude=.depend --exclude='.*.o.flags' --exclude='*.gz' --exclude=vmlinux --exclude=vmlinux.bin --exclude=yamon-02.06-SIGMADESIGNS-01_el.bin linuxmips-2.4.30.ref/fs/reiserfs/stree.c linuxmips-2.4.30/fs/reiserfs/stree.c
--- linuxmips-2.4.30.ref/fs/reiserfs/stree.c	2003-08-13 10:19:25.000000000 -0700
+++ linuxmips-2.4.30/fs/reiserfs/stree.c	2005-07-22 09:36:02.000000000 -0700
@@ -652,9 +652,8 @@
                                        stop at leaf level - set to
                                        DISK_LEAF_NODE_LEVEL */
     ) {
-    int  n_block_number = SB_ROOT_BLOCK (p_s_sb),
-      expected_level = SB_TREE_HEIGHT (p_s_sb),
-      n_block_size    = p_s_sb->s_blocksize;
+    int n_block_number, expected_level;
+    int n_block_size    = p_s_sb->s_blocksize;
     struct buffer_head  *       p_s_bh;
     struct path_element *       p_s_last_element;
     int				n_node_level, n_retval;
@@ -666,7 +665,8 @@
 #endif
     
     PROC_INFO_INC( p_s_sb, search_by_key );
-    
+    conditional_schedule();
+
     /* As we add each node to a path we increase its count.  This means that
        we must be careful to release all nodes in a path before we either
        discard the path struct or re-use the path struct, as we do here. */
@@ -678,6 +678,8 @@
     /* With each iteration of this loop we search through the items in the
        current node, and calculate the next current node(next path element)
        for the next iteration of this loop.. */
+    n_block_number = SB_ROOT_BLOCK (p_s_sb);
+    expected_level = SB_TREE_HEIGHT (p_s_sb);
     while ( 1 ) {
 
 #ifdef CONFIG_REISERFS_CHECK
@@ -1104,6 +1106,8 @@
 	    for (n_counter = *p_n_removed;
 		 n_counter < n_unfm_number; n_counter++, p_n_unfm_pointer-- ) {
 
+		conditional_schedule();
+
 		if (item_moved (&s_ih, p_s_path)) {
 		    need_research = 1 ;
 		    break;
diff -Naur --exclude=CVS --exclude='*.o' --exclude='*.a' --exclude='*.so' --exclude='*.elf' --exclude=System.map --exclude=Makefile.d --exclude='*log' --exclude='*log2' --exclude='*~' --exclude='.*~' --exclude='.#*' --exclude='*.bak' --exclude='*.orig' --exclude='*.rej' --exclude='core.[0-9]*' --exclude=.depend --exclude='.*.o.flags' --exclude='*.gz' --exclude=.depend --exclude='.*.o.flags' --exclude='*.gz' --exclude=vmlinux --exclude=vmlinux.bin --exclude=yamon-02.06-SIGMADESIGNS-01_el.bin linuxmips-2.4.30.ref/include/linux/low-latency.h linuxmips-2.4.30/include/linux/low-latency.h
--- linuxmips-2.4.30.ref/include/linux/low-latency.h	1969-12-31 16:00:00.000000000 -0800
+++ linuxmips-2.4.30/include/linux/low-latency.h	2005-07-22 09:36:02.000000000 -0700
@@ -0,0 +1,109 @@
+/*
+ * include/linux/low-latency.h
+ *
+ * Andrew Morton <[e-mail]>
+ */
+
+#ifndef LOW_LATENCY_H_INCLUDED
+#define LOW_LATENCY_H_INCLUDED
+
+#if defined(CONFIG_LOLAT)
+#define LOWLATENCY_NEEDED	1
+#else
+#define LOWLATENCY_NEEDED	0
+#endif
+
+#if LOWLATENCY_NEEDED
+
+#include <linux/cache.h>		/* For ____cacheline_aligned */
+
+#ifdef CONFIG_LOLAT_SYSCTL
+extern struct low_latency_enable_struct {
+	int yep;
+} ____cacheline_aligned __enable_lowlatency;
+#define enable_lowlatency __enable_lowlatency.yep
+
+#else
+#define enable_lowlatency 1
+#endif
+
+/*
+ * Set this non-zero to generate low-latency instrumentation
+ */
+#define LOWLATENCY_DEBUG		0
+
+/*
+ * Set this non-zero for robustness testing
+ */
+#define LOWLATENCY_ALWAYS_SCHEDULE	0
+
+#if LOWLATENCY_DEBUG
+
+#if LOWLATENCY_ALWAYS_SCHEDULE
+#define conditional_schedule_needed() ((enable_lowlatency == 2) || (enable_lowlatency && current->need_resched))
+#else
+#define conditional_schedule_needed() (enable_lowlatency && current->need_resched)
+#endif
+
+struct lolat_stats_t {
+	unsigned long count;
+	int visited;
+	const char *file;
+	int line;
+	struct lolat_stats_t *next;
+};
+
+void set_running_and_schedule(struct lolat_stats_t *stats);
+
+#define unconditional_schedule()					\
+	do {								\
+		static struct lolat_stats_t stats = {			\
+			file: __FILE__,					\
+			line: __LINE__,					\
+		};							\
+		set_running_and_schedule(&stats);			\
+	} while (0)
+
+extern void show_lolat_stats(void);
+
+#else	/* LOWLATENCY_DEBUG */
+
+#if LOWLATENCY_ALWAYS_SCHEDULE
+#define conditional_schedule_needed() 1
+#else
+#define conditional_schedule_needed() (current->need_resched)
+#endif