On Wednesday 01 August 2001 13:51, Mike Black wrote:
> I have come to the opinion that kswapd needs to be a little smarter
> -- if it doesn't find anything to swap shouldn't it go to sleep a
> little longer before trying again? That way it could gracefully
> degrade itself when it's not making any progress.
>
> In my testing (on a dual 1Ghz/2G machine) the machine "locks up" for
> long periods of time while kswapd runs around trying to do it's
> thing. If I could disable kswapd I would just to test this.
Your wish is my command. This patch provides a crude-but-effective
method of disabling kswapd, using:
echo 1 >/proc/sys/kernel/disable_kswapd
I tested this with dbench and found it runs about half as fast, but
runs. This is reassuring because kswapd is supposed to be doing
something useful.
To apply:
cd /usr/src/your.2.4.7.tree
patch -p0 <this.patch
--- ../2.4.7.clean/include/linux/swap.h Fri Jul 20 21:52:18 2001
+++ ./include/linux/swap.h Wed Aug 1 19:35:27 2001
@@ -78,6 +78,7 @@
int next; /* next entry on swap list */
};
+extern int disable_kswapd;
extern int nr_swap_pages;
extern unsigned int nr_free_pages(void);
extern unsigned int nr_inactive_clean_pages(void);
--- ../2.4.7.clean/include/linux/sysctl.h Fri Jul 20 21:52:18 2001
+++ ./include/linux/sysctl.h Wed Aug 1 19:35:28 2001
@@ -118,7 +118,8 @@
KERN_SHMPATH=48, /* string: path to shm fs */
KERN_HOTPLUG=49, /* string: path to hotplug policy agent */
KERN_IEEE_EMULATION_WARNINGS=50, /* int: unimplemented ieee
instructions */
- KERN_S390_USER_DEBUG_LOGGING=51 /* int: dumps of user faults */
+ KERN_S390_USER_DEBUG_LOGGING=51, /* int: dumps of user faults */
+ KERN_DISABLE_KSWAPD=52, /* int: disable kswapd for testing */
};
--- ../2.4.7.clean/kernel/sysctl.c Thu Apr 12 21:20:31 2001
+++ ./kernel/sysctl.c Wed Aug 1 19:35:28 2001
@@ -249,6 +249,8 @@
{KERN_S390_USER_DEBUG_LOGGING,"userprocess_debug",
&sysctl_userprocess_debug,sizeof(int),0644,NULL,&proc_dointvec},
#endif
+ {KERN_DISABLE_KSWAPD, "disable_kswapd", &disable_kswapd, sizeof (int),
+ 0644, NULL, &proc_dointvec},
{0}
};
--- ../2.4.7.clean/mm/vmscan.c Mon Jul 9 19:18:50 2001
+++ ./mm/vmscan.c Wed Aug 1 19:35:28 2001
@@ -875,6 +875,8 @@
DECLARE_WAIT_QUEUE_HEAD(kswapd_wait);
DECLARE_WAIT_QUEUE_HEAD(kswapd_done);
+int disable_kswapd /* = 0 */;
+
/*
* The background pageout daemon, started as a kernel thread
* from the init process.
@@ -915,6 +917,9 @@
*/
for (;;) {
static long recalc = 0;
+
+ while (disable_kswapd)
+ interruptible_sleep_on_timeout(&kswapd_wait, HZ/10);
/* If needed, try to free some memory. */
if (inactive_shortage() || free_shortage())
-
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This archive was generated by hypermail 2b29 : Tue Aug 07 2001 - 21:00:12 EST