Re: Calling sys_sysinfo from sched.c

["A.M. Fradley" <u2amf@xxxxxxxxxxxxx>]

// sched.c

unsigned long swpRtTimer = 0;

/*
 * The end of void scheduler_tick(void)
 */
out:
	rebalance_tick(cpu, rq, NOT_IDLE);
	if (jiffies > swpRtTimer) {
		getSwapRate();
		swpsPerJff();
		swpRtTimer = jiffies+HZ;
	}
}

/*
 * Measure how much swapping it being done.  ~AMF
 */
unsigned long getSwapRate(void) {
	swapRate = (swapRate + swapCount) >> 1;
	printk(KERN_CRIT "Swap rate is: %u\n", swapRate);
	printk(KERN_CRIT "Swap count was: %u\n", swapRate);
	swapCount = 0;
	return swapRate;
}

/*
 * An alternative, but probably less accurate.
 */
unsigned long swpsPerJff(void) {
	if (tSncLastSwp) {
		unsigned long scaleSwaps = 100 / tSncLastSwp;
		nr_swaps = (nr_swaps + scaleSwaps) >> 1;
	}
	return nr_swaps;
}


// memory.c

/*
 * Time of last swap/majflt,
 * Time since last swap/majflt,
 * Number of swaps since last swapRate() call,
 * Average number of swaps per swapRate() call,
 * Average number of swaps estimated by swpsPerJff()
 */
unsigned long tLastSwp = 0;
unsigned long tSncLastSwp = 0;
unsigned long swapCount = 0;
unsigned long swapRate = 0;
unsigned long nr_swaps = 0;

/*
 * It did this with the other externs so I assumed I should 
 * with mine as well.
 */
EXPORT_SYMBOL(tLastSwp);
EXPORT_SYMBOL(tSncLastSwp);
EXPORT_SYMBOL(swapCount);
EXPORT_SYMBOL(swapRate);
EXPORT_SYMBOL(nr_swaps);

/*
 * At the end of do_swap_page:
 */
out:
	if (ret == VM_FAULT_MAJOR) {
		tSncLastSwp = jiffies - tLastSwp;
		tLastSwp = jiffies;
		swapCount++;
		// printk(KERN_CRIT "Swap occured at time: %u\n", tLastSwp);
		printk(KERN_CRIT "Jiffies since last swap: %u\n\n", tSncLastSwp);
	}
	return ret;
}

// mm.h

extern unsigned long tLastSwp;
extern unsigned long tLastSwp;
extern unsigned long tSncLastSwp;
extern unsigned long swapCount;
extern unsigned long swapRate;
extern unsigned long nr_swaps;

// sched.h after scheduler_tick is declared.

extern unsigned long getSwapRate(void);
extern unsigned long swpsPerJff(void);


So that's what I think I can use to activate/deactivate the swap token
mechanism.  I'm not sure how accurate it is bit it definatly seems to notice
when there's a lot of programs opening and closing.  It's hard to tell if this
is a good way of measuring the vm pressure/load or not at the moment.  If
anyone knows of something that can stress test this, I could get a better
idea.


----------------------------------------------------------------
This message was sent using IMP, the Internet Messaging Program.

--
Kernelnewbies: Help each other learn about the Linux kernel.
Archive:       http://mail.nl.linux.org/kernelnewbies/
FAQ:           http://kernelnewbies.org/faq/