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Re: New patch (was Re: [PATCH] swapin readahead v3 + kswapd fixes)
On Sun, 20 Dec 1998, Linus Torvalds wrote:
>I expect that it needs to be tested in different configurations to find
>the optimal values for various tunables, but hopefully this is it when it
>comes to basic code.
I've done some changes to your code. The most experimental (easily
removable from the patch) is to move the check_pgt_cache() at the top of
the try_to/kswapd engines. This way we' ll trim the page table cache only
when we are low on memory, there's no reason to reclaim memory until there
is other memory unused I think.
The patch add also a bit of stats to the swap cache find case.
The real difference is to change the priority of try_to_free_pages() to 4
since this way we more probably allow process to continue their work
without to sleep for a lot of time waiting for SYNC I/O completation.
I also revert to shrink_mmap() if the async IO queue request is saturated.
Seems to work fine here...
Index: linux/mm/memory.c
diff -u linux/mm/memory.c:1.1.1.2 linux/mm/memory.c:1.1.1.1.2.6
--- linux/mm/memory.c:1.1.1.2 Fri Nov 27 11:19:10 1998
+++ linux/mm/memory.c Sun Dec 20 23:42:16 1998
@@ -136,8 +136,10 @@
for (i = 0 ; i < USER_PTRS_PER_PGD ; i++)
free_one_pgd(page_dir + i);
+#if 0 /* let kswapd to do this */
/* keep the page table cache within bounds */
check_pgt_cache();
+#endif
return;
out_bad:
@@ -165,8 +167,10 @@
free_one_pgd(page_dir + i);
pgd_free(page_dir);
+#if 0 /* let kswapd to do this */
/* keep the page table cache within bounds */
check_pgt_cache();
+#endif
out:
return;
Index: linux/mm/swap_state.c
diff -u linux/mm/swap_state.c:1.1.1.3 linux/mm/swap_state.c:1.1.1.1.2.7
--- linux/mm/swap_state.c:1.1.1.3 Sun Dec 20 16:31:12 1998
+++ linux/mm/swap_state.c Sun Dec 20 16:51:32 1998
@@ -261,6 +261,9 @@
struct page * lookup_swap_cache(unsigned long entry)
{
struct page *found;
+#ifdef SWAP_CACHE_INFO
+ swap_cache_find_total++;
+#endif
while (1) {
found = find_page(&swapper_inode, entry);
@@ -268,8 +271,12 @@
return 0;
if (found->inode != &swapper_inode || !PageSwapCache(found))
goto out_bad;
- if (!PageLocked(found))
+ if (!PageLocked(found)) {
+#ifdef SWAP_CACHE_INFO
+ swap_cache_find_success++;
+#endif
return found;
+ }
__free_page(found);
__wait_on_page(found);
}
Index: linux/mm/vmscan.c
diff -u linux/mm/vmscan.c:1.1.1.5 linux/mm/vmscan.c:1.1.1.1.2.33
--- linux/mm/vmscan.c:1.1.1.5 Sun Dec 20 16:31:12 1998
+++ linux/mm/vmscan.c Mon Dec 21 10:25:22 1998
@@ -447,11 +447,12 @@
/* Always trim SLAB caches when memory gets low. */
kmem_cache_reap(0);
+ check_pgt_cache();
/* max one hundreth of a second */
end_time = jiffies + (HZ-1)/100;
do {
- int priority = 7;
+ int priority = 6;
int count = pager_daemon.swap_cluster;
switch (kswapd_state) {
@@ -476,6 +477,12 @@
return kswapd_state;
}
+static inline void enable_swap_tick(void)
+{
+ timer_table[SWAP_TIMER].expires = jiffies;
+ timer_active |= 1<<SWAP_TIMER;
+}
+
/*
* The background pageout daemon.
* Started as a kernel thread from the init process.
@@ -523,6 +530,7 @@
current->state = TASK_INTERRUPTIBLE;
flush_signals(current);
run_task_queue(&tq_disk);
+ enable_swap_tick();
schedule();
swapstats.wakeups++;
state = kswapd_free_pages(state);
@@ -553,6 +561,7 @@
lock_kernel();
+ check_pgt_cache();
/* Always trim SLAB caches when memory gets low. */
kmem_cache_reap(gfp_mask);
@@ -562,7 +571,7 @@
current->flags |= PF_MEMALLOC;
- priority = 8;
+ priority = 4;
do {
free_memory(shrink_mmap(priority, gfp_mask));
free_memory(shm_swap(priority, gfp_mask));
@@ -593,7 +602,8 @@
if (priority) {
p->counter = p->priority << priority;
wake_up_process(p);
- }
+ } else
+ enable_swap_tick();
}
/*
@@ -631,9 +641,8 @@
want_wakeup = 3;
kswapd_wakeup(p,want_wakeup);
- }
-
- timer_active |= (1<<SWAP_TIMER);
+ } else
+ enable_swap_tick();
}
/*
Index: linux/arch/i386/kernel/process.c
diff -u linux/arch/i386/kernel/process.c:1.1.1.4 linux/arch/i386/kernel/process.c:1.1.1.1.2.32
--- linux/arch/i386/kernel/process.c:1.1.1.4 Thu Dec 17 16:33:27 1998
+++ linux/arch/i386/kernel/process.c Mon Dec 21 10:35:52 1998
@@ -73,11 +73,11 @@
#ifndef __SMP__
+#ifdef CONFIG_APM
static void hard_idle(void)
{
while (!current->need_resched) {
if (boot_cpu_data.hlt_works_ok && !hlt_counter) {
-#ifdef CONFIG_APM
/* If the APM BIOS is not enabled, or there
is an error calling the idle routine, we
should hlt if possible. We need to check
@@ -87,44 +87,50 @@
if (!apm_do_idle() && !current->need_resched)
__asm__("hlt");
end_bh_atomic();
-#else
- __asm__("hlt");
-#endif
}
if (current->need_resched)
break;
schedule();
}
-#ifdef CONFIG_APM
apm_do_busy();
-#endif
}
+#endif
/*
* The idle loop on a uniprocessor i386..
*/
static int cpu_idle(void *unused)
{
+#ifdef CONFIG_APM
int work = 1;
unsigned long start_idle = 0;
+#endif
+ long * need_resched = ¤t->need_resched;
/* endless idle loop with no priority at all */
current->priority = 0;
current->counter = -100;
for (;;) {
+#ifdef CONFIG_APM
if (work)
start_idle = jiffies;
if (jiffies - start_idle > HARD_IDLE_TIMEOUT)
hard_idle();
else {
- if (boot_cpu_data.hlt_works_ok && !hlt_counter && !current->need_resched)
+#endif
+ if (boot_cpu_data.hlt_works_ok && !hlt_counter && !*need_resched)
__asm__("hlt");
+
+#ifdef CONFIG_APM
}
- work = current->need_resched;
+ work = *need_resched;
+#endif
schedule();
+#if 0
check_pgt_cache();
+#endif
}
}
@@ -136,14 +142,18 @@
int cpu_idle(void *unused)
{
+ long * need_resched = ¤t->need_resched;
+
/* endless idle loop with no priority at all */
current->priority = 0;
current->counter = -100;
while(1) {
- if (current_cpu_data.hlt_works_ok && !hlt_counter && !current->need_resched)
+ if (current_cpu_data.hlt_works_ok && !hlt_counter && !*need_resched)
__asm__("hlt");
schedule();
+#if 0
check_pgt_cache();
+#endif
}
}
Andrea Arcangeli
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