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From: Mark Johnston <markj@FreeBSD.org>
Date: Mon, 17 Oct 2016 07:23:07 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-user@freebsd.org
Subject: svn commit: r307488 - user/alc/PQ_LAUNDRY/sys/vm
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Author: markj
Date: Mon Oct 17 07:23:07 2016
New Revision: 307488
URL: https://svnweb.freebsd.org/changeset/base/307488
Log:
Handle laundering run preemption properly.
Shortfall can preempt a background laundering, but not a shortfall
laundering. Therefore:
- make sure we don't reset the shortfall target if a shortfall request
arrives while the system is already in shortfall, and
- make sure we acknowledge a shortfall request by resetting
vm_laundry_request if it arrives during background laundering.
Also ensure that we sleep uninterruptibly between laundry cycles, and
rename "cycle" to make its use more clear.
Reviewed by: alc
Modified:
user/alc/PQ_LAUNDRY/sys/vm/vm_pageout.c
Modified: user/alc/PQ_LAUNDRY/sys/vm/vm_pageout.c
==============================================================================
--- user/alc/PQ_LAUNDRY/sys/vm/vm_pageout.c Mon Oct 17 07:20:01 2016 (r307487)
+++ user/alc/PQ_LAUNDRY/sys/vm/vm_pageout.c Mon Oct 17 07:23:07 2016 (r307488)
@@ -1115,8 +1115,7 @@ vm_pageout_laundry_worker(void *arg)
struct vm_pagequeue *pq;
uint64_t nclean, ndirty;
u_int last_launder, wakeups;
- int cycle, domidx, last_target, launder, shortfall;
- int sleeptime, target;
+ int domidx, last_target, launder, shortfall, shortfall_cycle, target;
bool in_shortfall;
domidx = (uintptr_t)arg;
@@ -1127,8 +1126,8 @@ vm_pageout_laundry_worker(void *arg)
shortfall = 0;
in_shortfall = false;
+ shortfall_cycle = 0;
target = 0;
- cycle = 0;
last_launder = 0;
/*
@@ -1136,7 +1135,8 @@ vm_pageout_laundry_worker(void *arg)
*/
for (;;) {
KASSERT(target >= 0, ("negative target %d", target));
- KASSERT(cycle >= 0, ("negative cycle %d", cycle));
+ KASSERT(shortfall_cycle >= 0,
+ ("negative cycle %d", shortfall_cycle));
launder = 0;
wakeups = VM_METER_PCPU_CNT(v_pdwakeups);
@@ -1146,11 +1146,11 @@ vm_pageout_laundry_worker(void *arg)
*/
if (shortfall > 0) {
in_shortfall = true;
+ shortfall_cycle = VM_LAUNDER_RATE;
target = shortfall;
- cycle = VM_LAUNDER_RATE;
} else if (!in_shortfall)
goto trybackground;
- else if (cycle == 0 || vm_laundry_target() <= 0) {
+ else if (shortfall_cycle == 0 || vm_laundry_target() <= 0) {
/*
* We recently entered shortfall and began laundering
* pages. If we have completed that laundering run
@@ -1163,7 +1163,7 @@ vm_pageout_laundry_worker(void *arg)
goto trybackground;
}
last_launder = wakeups;
- launder = target / cycle--;
+ launder = target / shortfall_cycle--;
goto dolaundry;
/*
@@ -1229,16 +1229,26 @@ dolaundry:
* started. Otherwise, wait for a kick from the pagedaemon.
*/
vm_pagequeue_lock(pq);
- if (target > 0 || vm_laundry_request != VM_LAUNDRY_IDLE)
- sleeptime = hz / VM_LAUNDER_INTERVAL;
- else
- sleeptime = 0;
- (void)mtx_sleep(&vm_laundry_request, vm_pagequeue_lockptr(pq),
- PVM, "laundr", sleeptime);
- if (vm_laundry_request == VM_LAUNDRY_SHORTFALL)
+ if (target > 0 || vm_laundry_request != VM_LAUNDRY_IDLE) {
+ vm_pagequeue_unlock(pq);
+ pause("laundr", hz / VM_LAUNDER_INTERVAL);
+ vm_pagequeue_lock(pq);
+ } else
+ (void)mtx_sleep(&vm_laundry_request,
+ vm_pagequeue_lockptr(pq), PVM, "laundr", 0);
+
+ /*
+ * If the pagedaemon has indicated that it's in shortfall, start
+ * a shortfall laundering unless we're already in the middle of
+ * one. This may preempt a background laundering.
+ */
+ if (vm_laundry_request == VM_LAUNDRY_SHORTFALL &&
+ (!in_shortfall || shortfall_cycle == 0)) {
shortfall = vm_laundry_target() + vm_pageout_deficit;
- else
+ target = 0;
+ } else
shortfall = 0;
+
if (target == 0)
vm_laundry_request = VM_LAUNDRY_IDLE;
vm_pagequeue_unlock(pq);