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Use pg_pread() and pg_pwrite() in slru.c. 

This avoids lseek() system calls at every SLRU I/O, as was
done for relation files in commit c24dcd0c.

Reviewed-by: Ashwin Agrawal <aagrawal@pivotal.io>
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/CA%2BhUKG%2Biqke4uTRFj8D8uEUUgj%2BRokPSp%2BCWM6YYzaaamG9Wvg%40mail.gmail.com
Discussion: https://postgr.es/m/CA%2BhUKGJ%2BoHhnvqjn3%3DHro7xu-YDR8FPr0FL6LF35kHRX%3D_bUzg%40mail.gmail.com
This commit is contained in:
Thomas Munro 2020-08-01 23:39:36 +12:00
parent 022350b849
commit e2b37d9e7c
1 changed files with 4 additions and 21 deletions
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25
src/backend/access/transam/slru.c
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@ -669,7 +669,7 @@ SlruPhysicalReadPage(SlruCtl ctl, int pageno, int slotno)
SlruShared shared = ctl->shared;
int segno = pageno / SLRU_PAGES_PER_SEGMENT;
int rpageno = pageno % SLRU_PAGES_PER_SEGMENT;
int offset = rpageno * BLCKSZ;
off_t offset = rpageno * BLCKSZ;
char path[MAXPGPATH];
int fd;
@ -699,17 +699,9 @@ SlruPhysicalReadPage(SlruCtl ctl, int pageno, int slotno)
return true;
}
if (lseek(fd, (off_t) offset, SEEK_SET) < 0)
{
slru_errcause = SLRU_SEEK_FAILED;
slru_errno = errno;
CloseTransientFile(fd);
return false;
}
errno = 0;
pgstat_report_wait_start(WAIT_EVENT_SLRU_READ);
if (read(fd, shared->page_buffer[slotno], BLCKSZ) != BLCKSZ)
if (pg_pread(fd, shared->page_buffer[slotno], BLCKSZ, offset) != BLCKSZ)
{
pgstat_report_wait_end();
slru_errcause = SLRU_READ_FAILED;
@ -749,7 +741,7 @@ SlruPhysicalWritePage(SlruCtl ctl, int pageno, int slotno, SlruFlush fdata)
SlruShared shared = ctl->shared;
int segno = pageno / SLRU_PAGES_PER_SEGMENT;
int rpageno = pageno % SLRU_PAGES_PER_SEGMENT;
int offset = rpageno * BLCKSZ;
off_t offset = rpageno * BLCKSZ;
char path[MAXPGPATH];
int fd = -1;
@ -862,18 +854,9 @@ SlruPhysicalWritePage(SlruCtl ctl, int pageno, int slotno, SlruFlush fdata)
}
}
if (lseek(fd, (off_t) offset, SEEK_SET) < 0)
{
slru_errcause = SLRU_SEEK_FAILED;
slru_errno = errno;
if (!fdata)
CloseTransientFile(fd);
return false;
}
errno = 0;
pgstat_report_wait_start(WAIT_EVENT_SLRU_WRITE);
if (write(fd, shared->page_buffer[slotno], BLCKSZ) != BLCKSZ)
if (pg_pwrite(fd, shared->page_buffer[slotno], BLCKSZ, offset) != BLCKSZ)
{
pgstat_report_wait_end();
/* if write didn't set errno, assume problem is no disk space */