Linux-kernel mailing list archive 1999-37,: [patch] kupdate for 2.3.18ac2

# [patch] kupdate for 2.3.18ac2

Andrea Arcangeli (andrea@suse.de)
Tue, 14 Sep 1999 01:51:53 +0200 (CEST)

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I ported kupdate to 2.3.18ac2. It has the advantages of the 2.2.10 version
plus in 2.3.x it avoids to flush the tlb before going to sleep.

This one can be really stopped and started via SIGSTOP/SIGCONT (by root
ouf course ;).

It will go to sleep in SIGSTOP mode if the interval will be set to zero.
So if you set interval to zero and then after some time you set interval
!= 0 then you'll have to send a SIGCONT to kupdate to make it again
functional.

Patch against 2.3.18ac2:

--- 2.3.18ac2-kupdate/fs/buffer.c.~1~ Mon Sep 13 03:38:46 1999
+++ 2.3.18ac2-kupdate/fs/buffer.c Tue Sep 14 00:33:14 1999
@@ -114,18 +114,18 @@
each time we call refill */
int nref_dirt; /* Dirty buffer threshold for activating bdflush
when trying to refill buffers. */
- int dummy1; /* unused */
+ int interval; /* jiffies delay between kupdate flushes */
int age_buffer; /* Time for normal buffer to age before we flush it */
int age_super; /* Time for superblock to age before we flush it */
int dummy2; /* unused */
int dummy3; /* unused */
} b_un;
unsigned int data[N_PARAM];
-} bdf_prm = {{40, 500, 64, 256, 15, 30*HZ, 5*HZ, 1884, 2}};
+} bdf_prm = {{40, 500, 64, 256, 5*HZ, 30*HZ, 5*HZ, 1884, 2}};
/* These are the min and max parameter values that we will allow to be assigned */
int bdflush_min[N_PARAM] = { 0, 10, 5, 25, 0, 1*HZ, 1*HZ, 1, 1};
-int bdflush_max[N_PARAM] = {100,50000, 20000, 20000,1000, 6000*HZ, 6000*HZ, 2047, 5};
+int bdflush_max[N_PARAM] = {100,50000, 20000, 20000,600*HZ, 6000*HZ, 6000*HZ, 2047, 5};
void wakeup_bdflush(int);
@@ -2313,6 +2313,10 @@
return -EPERM;
if (func == 1) {
+ /* do_exit directly and let kupdate to do its work alone. */
+ do_exit(0);
+#if 0 /* left here as it's the only example of lazy-mm-stuff used from
+ a syscall that doesn't care about the current mm context. */
int error;
struct mm_struct *user_mm;
@@ -2326,6 +2330,7 @@
error = sync_old_buffers();
end_lazy_tlb(user_mm);
return error;
+#endif
}
/* Basically func 1 means read param 1, 2 means write param 1, etc */
@@ -2444,9 +2449,68 @@
}
}
+/*
+ * This is the kernel update daemon. It was used to live in userspace
+ * but since it's need to run safely we want it unkillable by mistake.
+ * You don't need to change your userspace configuration since
+ * the userspace `update` will do_exit(0) at the first sys_bdflush().
+ */
+int kupdate(void * unused)
+{
+ struct task_struct * tsk = current;
+ int interval;
+
+ tsk->session = 1;
+ tsk->pgrp = 1;
+ strcpy(tsk->comm, "kupdate");
+
+ /* sigstop and sigcont will stop and wakeup kupdate */
+ spin_lock_irq(&tsk->sigmask_lock);
+ sigfillset(&tsk->blocked);
+ siginitsetinv(&current->blocked, sigmask(SIGCONT) | sigmask(SIGSTOP));
+ recalc_sigpending(tsk);
+ spin_unlock_irq(&tsk->sigmask_lock);
+
+ for (;;) {
+ /* update interval */
+ interval = bdf_prm.b_un.interval;
+ if (interval)
+ {
+ tsk->state = TASK_INTERRUPTIBLE;
+ schedule_timeout(interval);
+ }
+ else
+ {
+ stop_kupdate:
+ tsk->state = TASK_STOPPED;
+ schedule(); /* wait for SIGCONT */
+ }
+ /* check for sigstop */
+ if (signal_pending(tsk))
+ {
+ int stopped = 0;
+ spin_lock_irq(&tsk->sigmask_lock);
+ if (sigismember(&tsk->signal, SIGSTOP))
+ {
+ sigdelset(&tsk->signal, SIGSTOP);
+ stopped = 1;
+ }
+ recalc_sigpending(tsk);
+ spin_unlock_irq(&tsk->sigmask_lock);
+ if (stopped)
+ goto stop_kupdate;
+ }
+#ifdef DEBUG
+ printk("kupdate() activated...\n");
+#endif
+ sync_old_buffers();
+ }
+}
+
static int __init bdflush_init(void)
{
kernel_thread(bdflush, NULL, CLONE_FS | CLONE_FILES | CLONE_SIGHAND);
+ kernel_thread(kupdate, NULL, CLONE_FS | CLONE_FILES | CLONE_SIGHAND);
return 0;
}

Andrea

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