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Drop & re-acquire vmobjlock less often.

This commit is contained in:
ad 2020-05-19 21:45:35 +00:00
parent d6e424b62c
commit 5ba8a0826b
1 changed files with 7 additions and 7 deletions
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14
sys/uvm/uvm_readahead.c
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@ -1,4 +1,4 @@
/* $NetBSD: uvm_readahead.c,v 1.12 2020/03/08 18:40:29 ad Exp $ */
/* $NetBSD: uvm_readahead.c,v 1.13 2020/05/19 21:45:35 ad Exp $ */
/*-
* Copyright (c)2003, 2005, 2009 YAMAMOTO Takashi,
@ -40,7 +40,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: uvm_readahead.c,v 1.12 2020/03/08 18:40:29 ad Exp $");
__KERNEL_RCSID(0, "$NetBSD: uvm_readahead.c,v 1.13 2020/05/19 21:45:35 ad Exp $");
#include <sys/param.h>
#include <sys/pool.h>
@ -126,6 +126,8 @@ ra_startio(struct uvm_object *uobj, off_t off, size_t sz)
DPRINTF(("%s: uobj=%p, off=%" PRIu64 ", endoff=%" PRIu64 "\n",
__func__, uobj, off, endoff));
KASSERT(rw_write_held(uobj->vmobjlock));
/*
* Don't issue read-ahead if the last page of the range is already cached.
* The assumption is that since the access is sequential, the intermediate
@ -133,9 +135,7 @@ ra_startio(struct uvm_object *uobj, off_t off, size_t sz)
* too. This speeds up I/O using cache, since it avoids lookups and temporary
* allocations done by full pgo_get.
*/
rw_enter(uobj->vmobjlock, RW_READER);
struct vm_page *pg = uvm_pagelookup(uobj, trunc_page(endoff - 1));
rw_exit(uobj->vmobjlock);
if (pg != NULL) {
DPRINTF(("%s: off=%" PRIu64 ", sz=%zu already cached\n",
__func__, off, sz));
@ -162,9 +162,9 @@ ra_startio(struct uvm_object *uobj, off_t off, size_t sz)
* use UVM_ADV_RANDOM to avoid recursion.
*/
rw_enter(uobj->vmobjlock, RW_WRITER);
error = (*uobj->pgops->pgo_get)(uobj, off, NULL,
&npages, 0, VM_PROT_READ, UVM_ADV_RANDOM, PGO_NOTIMESTAMP);
rw_enter(uobj->vmobjlock, RW_WRITER);
DPRINTF(("%s: off=%" PRIu64 ", bytelen=%zu -> %d\n",
__func__, off, bytelen, error));
if (error != 0 && error != EBUSY) {
@ -332,9 +332,7 @@ do_readahead:
if (rasize >= RA_MINSIZE) {
off_t next;
rw_exit(uobj->vmobjlock);
next = ra_startio(uobj, raoff, rasize);
rw_enter(uobj->vmobjlock, RW_WRITER);
ra->ra_next = next;
}
}
@ -362,6 +360,8 @@ uvm_readahead(struct uvm_object *uobj, off_t off, off_t size)
if (size > RA_WINSIZE_MAX) {
size = RA_WINSIZE_MAX;
}
rw_enter(uobj->vmobjlock, RW_WRITER);
ra_startio(uobj, off, size);
rw_exit(uobj->vmobjlock);
return 0;
}