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Restore an optimization that was temporary disabled by r324665.

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In reclaim_pv_chunk(), rotate the pv chunks list so that next
invocations of the reclaim do not scan the same pv chunks that could
not be freed.  Only do the rotation when there is no parallel scan,
tracked by active_reclaims counter.

To rotate, move all chunks that are before current iteration marker,
after another marker that is inserted at the list tail on start of the
reclaim.

Reviewed by:	alc
Tested by:	pho (previous version)
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
This commit is contained in:
kib 2017-11-01 18:06:44 +00:00
parent 5f19587fba
commit e5cf015156
1 changed files with 32 additions and 4 deletions
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36
sys/amd64/amd64/pmap.c
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@ -2892,8 +2892,8 @@ reclaim_pv_chunk_leave_pmap(pmap_t pmap, pmap_t locked_pmap, bool start_di)
static vm_page_t
reclaim_pv_chunk(pmap_t locked_pmap, struct rwlock **lockp)
{
struct pv_chunk *pc, *pc_marker;
struct pv_chunk_header pc_marker_b;
struct pv_chunk *pc, *pc_marker, *pc_marker_end;
struct pv_chunk_header pc_marker_b, pc_marker_end_b;
struct md_page *pvh;
pd_entry_t *pde;
pmap_t next_pmap, pmap;
@ -2906,6 +2906,7 @@ reclaim_pv_chunk(pmap_t locked_pmap, struct rwlock **lockp)
uint64_t inuse;
int bit, field, freed;
bool start_di;
static int active_reclaims = 0;
PMAP_LOCK_ASSERT(locked_pmap, MA_OWNED);
KASSERT(lockp != NULL, ("reclaim_pv_chunk: lockp is NULL"));
@ -2914,7 +2915,9 @@ reclaim_pv_chunk(pmap_t locked_pmap, struct rwlock **lockp)
PG_G = PG_A = PG_M = PG_RW = 0;
SLIST_INIT(&free);
bzero(&pc_marker_b, sizeof(pc_marker_b));
bzero(&pc_marker_end, sizeof(pc_marker_end));
pc_marker = (struct pv_chunk *)&pc_marker_b;
pc_marker_end = (struct pv_chunk *)&pc_marker_end_b;
/*
* A delayed invalidation block should already be active if
@ -2924,12 +2927,21 @@ reclaim_pv_chunk(pmap_t locked_pmap, struct rwlock **lockp)
start_di = pmap_not_in_di();
mtx_lock(&pv_chunks_mutex);
active_reclaims++;
TAILQ_INSERT_HEAD(&pv_chunks, pc_marker, pc_lru);
while ((pc = TAILQ_NEXT(pc_marker, pc_lru)) != NULL &&
TAILQ_INSERT_TAIL(&pv_chunks, pc_marker_end, pc_lru);
while ((pc = TAILQ_NEXT(pc_marker, pc_lru)) != pc_marker_end &&
SLIST_EMPTY(&free)) {
next_pmap = pc->pc_pmap;
if (next_pmap == NULL) /* marker */
if (next_pmap == NULL) {
/*
* The next chunk is a marker. However, it is
* not our marker, so active_reclaims must be
* > 1. Consequently, the next_chunk code
* will not rotate the pv_chunks list.
*/
goto next_chunk;
}
mtx_unlock(&pv_chunks_mutex);
/*
@ -3043,8 +3055,24 @@ reclaim_pv_chunk(pmap_t locked_pmap, struct rwlock **lockp)
next_chunk:
TAILQ_REMOVE(&pv_chunks, pc_marker, pc_lru);
TAILQ_INSERT_AFTER(&pv_chunks, pc, pc_marker, pc_lru);
if (active_reclaims == 1 && pmap != NULL) {
/*
* Rotate the pv chunks list so that we do not
* scan the same pv chunks that could not be
* freed (because they contained a wired
* and/or superpage mapping) on every
* invocation of reclaim_pv_chunk().
*/
while ((pc = TAILQ_FIRST(&pv_chunks)) != pc_marker) {
MPASS(pc->pc_pmap != NULL);
TAILQ_REMOVE(&pv_chunks, pc, pc_lru);
TAILQ_INSERT_TAIL(&pv_chunks, pc, pc_lru);
}
}
}
TAILQ_REMOVE(&pv_chunks, pc_marker, pc_lru);
TAILQ_REMOVE(&pv_chunks, pc_marker_end, pc_lru);
active_reclaims--;
mtx_unlock(&pv_chunks_mutex);
reclaim_pv_chunk_leave_pmap(pmap, locked_pmap, start_di);
if (m_pc == NULL && !SLIST_EMPTY(&free)) {