19.12.2024 15:10, Andrey M. Borodin wrote:
On 19 Dec 2024, at 15:37, Yura Sokolov <y.soko...@postgrespro.ru> wrote:
So, there's no more than 8192 banks at the moment.
OK, but still current type indicates bitwise usage, while struct member is used
as a number.
Ok, I agree. Here's version with type change bits16 -> uint16.
From 4a16d64fe6eba042bfca7ff0b0d73ec8b749e6e0 Mon Sep 17 00:00:00 2001
From: Yura Sokolov <y.soko...@postgrespro.ru>
Date: Tue, 10 Dec 2024 15:38:02 +0300
Subject: [PATCH v2] Fix SLRU bank selection.
Due to code evolution, nbanks is not power of two any more. But still
binary & were used to obtain bankno.
---
src/backend/access/transam/slru.c | 6 +++---
src/include/access/slru.h | 6 +++---
2 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/src/backend/access/transam/slru.c b/src/backend/access/transam/slru.c
index e7f73bf4275..afedb5c039f 100644
--- a/src/backend/access/transam/slru.c
+++ b/src/backend/access/transam/slru.c
@@ -343,7 +343,7 @@ SimpleLruInit(SlruCtl ctl, const char *name, int nslots, int nlsns,
ctl->shared = shared;
ctl->sync_handler = sync_handler;
ctl->long_segment_names = long_segment_names;
- ctl->bank_mask = (nslots / SLRU_BANK_SIZE) - 1;
+ ctl->nbanks = nbanks;
strlcpy(ctl->Dir, subdir, sizeof(ctl->Dir));
}
@@ -606,7 +606,7 @@ SimpleLruReadPage_ReadOnly(SlruCtl ctl, int64 pageno, TransactionId xid)
{
SlruShared shared = ctl->shared;
LWLock *banklock = SimpleLruGetBankLock(ctl, pageno);
- int bankno = pageno & ctl->bank_mask;
+ int bankno = pageno % ctl->nbanks;
int bankstart = bankno * SLRU_BANK_SIZE;
int bankend = bankstart + SLRU_BANK_SIZE;
@@ -1177,7 +1177,7 @@ SlruSelectLRUPage(SlruCtl ctl, int64 pageno)
int bestinvalidslot = 0; /* keep compiler quiet */
int best_invalid_delta = -1;
int64 best_invalid_page_number = 0; /* keep compiler quiet */
- int bankno = pageno & ctl->bank_mask;
+ int bankno = pageno % ctl->nbanks;
int bankstart = bankno * SLRU_BANK_SIZE;
int bankend = bankstart + SLRU_BANK_SIZE;
diff --git a/src/include/access/slru.h b/src/include/access/slru.h
index 97e612cd100..648e202ff54 100644
--- a/src/include/access/slru.h
+++ b/src/include/access/slru.h
@@ -129,9 +129,9 @@ typedef struct SlruCtlData
SlruShared shared;
/*
- * Bitmask to determine bank number from page number.
+ * Number of banks to determine bank number from page number.
*/
- bits16 bank_mask;
+ uint16 nbanks;
/*
* If true, use long segment file names. Otherwise, use short file names.
@@ -179,7 +179,7 @@ SimpleLruGetBankLock(SlruCtl ctl, int64 pageno)
{
int bankno;
- bankno = pageno & ctl->bank_mask;
+ bankno = pageno % ctl->nbanks;
return &(ctl->shared->bank_locks[bankno].lock);
}
--
2.43.0
