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Move each SLRU's lwlocks to a separate tranche.

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This makes it significantly easier to identify these lwlocks in
LWLOCK_STATS or Trace_lwlocks output.  It's also arguably better
from a modularity standpoint, since lwlock.c no longer needs to
know anything about the LWLock needs of the higher-level SLRU
facility.

Ildus Kurbangaliev, reviewd by Álvaro Herrera and by me.
This commit is contained in:
Robert Haas
2015-11-12 14:59:09 -05:00
parent c405918858
commit fe702a7b3f
9 changed files with 41 additions and 43 deletions
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37
src/backend/access/transam/slru.c
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@@ -152,7 +152,7 @@ SimpleLruShmemSize(int nslots, int nlsns)
sz += MAXALIGN(nslots * sizeof(bool)); /* page_dirty[] */
sz += MAXALIGN(nslots * sizeof(int)); /* page_number[] */
sz += MAXALIGN(nslots * sizeof(int)); /* page_lru_count[] */
sz += MAXALIGN(nslots * sizeof(LWLock *)); /* buffer_locks[] */
sz += MAXALIGN(nslots * sizeof(LWLockPadded)); /* buffer_locks[] */
if (nlsns > 0)
sz += MAXALIGN(nslots * nlsns * sizeof(XLogRecPtr)); /* group_lsn[] */
@@ -203,8 +203,6 @@ SimpleLruInit(SlruCtl ctl, const char *name, int nslots, int nlsns,
offset += MAXALIGN(nslots * sizeof(int));
shared->page_lru_count = (int *) (ptr + offset);
offset += MAXALIGN(nslots * sizeof(int));
shared->buffer_locks = (LWLock **) (ptr + offset);
offset += MAXALIGN(nslots * sizeof(LWLock *));
if (nlsns > 0)
{
@@ -212,20 +210,35 @@ SimpleLruInit(SlruCtl ctl, const char *name, int nslots, int nlsns,
offset += MAXALIGN(nslots * nlsns * sizeof(XLogRecPtr));
}
/* Initialize LWLocks */
shared->buffer_locks = (LWLockPadded *) ShmemAlloc(sizeof(LWLockPadded) * nslots);
Assert(strlen(name) + 1 < SLRU_MAX_NAME_LENGTH);
strlcpy(shared->lwlock_tranche_name, name, SLRU_MAX_NAME_LENGTH);
shared->lwlock_tranche_id = LWLockNewTrancheId();
shared->lwlock_tranche.name = shared->lwlock_tranche_name;
shared->lwlock_tranche.array_base = shared->buffer_locks;
shared->lwlock_tranche.array_stride = sizeof(LWLockPadded);
ptr += BUFFERALIGN(offset);
for (slotno = 0; slotno < nslots; slotno++)
{
LWLockInitialize(&shared->buffer_locks[slotno].lock,
shared->lwlock_tranche_id);
shared->page_buffer[slotno] = ptr;
shared->page_status[slotno] = SLRU_PAGE_EMPTY;
shared->page_dirty[slotno] = false;
shared->page_lru_count[slotno] = 0;
shared->buffer_locks[slotno] = LWLockAssign();
ptr += BLCKSZ;
}
}
else
Assert(found);
/* Register SLRU tranche in the main tranches array */
LWLockRegisterTranche(shared->lwlock_tranche_id, &shared->lwlock_tranche);
/*
* Initialize the unshared control struct, including directory path. We
* assume caller set PagePrecedes.
@@ -308,8 +321,8 @@ SimpleLruWaitIO(SlruCtl ctl, int slotno)
/* See notes at top of file */
LWLockRelease(shared->ControlLock);
LWLockAcquire(shared->buffer_locks[slotno], LW_SHARED);
LWLockRelease(shared->buffer_locks[slotno]);
LWLockAcquire(&shared->buffer_locks[slotno].lock, LW_SHARED);
LWLockRelease(&shared->buffer_locks[slotno].lock);
LWLockAcquire(shared->ControlLock, LW_EXCLUSIVE);
/*
@@ -323,7 +336,7 @@ SimpleLruWaitIO(SlruCtl ctl, int slotno)
if (shared->page_status[slotno] == SLRU_PAGE_READ_IN_PROGRESS ||
shared->page_status[slotno] == SLRU_PAGE_WRITE_IN_PROGRESS)
{
if (LWLockConditionalAcquire(shared->buffer_locks[slotno], LW_SHARED))
if (LWLockConditionalAcquire(&shared->buffer_locks[slotno].lock, LW_SHARED))
{
/* indeed, the I/O must have failed */
if (shared->page_status[slotno] == SLRU_PAGE_READ_IN_PROGRESS)
@@ -333,7 +346,7 @@ SimpleLruWaitIO(SlruCtl ctl, int slotno)
shared->page_status[slotno] = SLRU_PAGE_VALID;
shared->page_dirty[slotno] = true;
}
LWLockRelease(shared->buffer_locks[slotno]);
LWLockRelease(&shared->buffer_locks[slotno].lock);
}
}
}
@@ -402,7 +415,7 @@ SimpleLruReadPage(SlruCtl ctl, int pageno, bool write_ok,
shared->page_dirty[slotno] = false;
/* Acquire per-buffer lock (cannot deadlock, see notes at top) */
LWLockAcquire(shared->buffer_locks[slotno], LW_EXCLUSIVE);
LWLockAcquire(&shared->buffer_locks[slotno].lock, LW_EXCLUSIVE);
/* Release control lock while doing I/O */
LWLockRelease(shared->ControlLock);
@@ -422,7 +435,7 @@ SimpleLruReadPage(SlruCtl ctl, int pageno, bool write_ok,
shared->page_status[slotno] = ok ? SLRU_PAGE_VALID : SLRU_PAGE_EMPTY;
LWLockRelease(shared->buffer_locks[slotno]);
LWLockRelease(&shared->buffer_locks[slotno].lock);
/* Now it's okay to ereport if we failed */
if (!ok)
@@ -518,7 +531,7 @@ SlruInternalWritePage(SlruCtl ctl, int slotno, SlruFlush fdata)
shared->page_dirty[slotno] = false;
/* Acquire per-buffer lock (cannot deadlock, see notes at top) */
LWLockAcquire(shared->buffer_locks[slotno], LW_EXCLUSIVE);
LWLockAcquire(&shared->buffer_locks[slotno].lock, LW_EXCLUSIVE);
/* Release control lock while doing I/O */
LWLockRelease(shared->ControlLock);
@@ -547,7 +560,7 @@ SlruInternalWritePage(SlruCtl ctl, int slotno, SlruFlush fdata)
shared->page_status[slotno] = SLRU_PAGE_VALID;
LWLockRelease(shared->buffer_locks[slotno]);
LWLockRelease(&shared->buffer_locks[slotno].lock);
/* Now it's okay to ereport if we failed */
if (!ok)