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PR/14781: Matthew Fredette: Clamp the number of read-ahead pages to 16 because

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other code has this limit. Also while I am here, convert the magic 16 into
a #define constant and use it in the appropriate places. This is a temporary
fix, since all this read-ahead business is XXXUBC anyway.
This commit is contained in:
christos 2001-11-30 15:18:39 +00:00
parent 1a67790534
commit 420771d7cc
1 changed files with 13 additions and 7 deletions
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20
sys/miscfs/genfs/genfs_vnops.c
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@ -1,4 +1,4 @@
/* $NetBSD: genfs_vnops.c,v 1.40 2001/11/10 13:33:41 lukem Exp $ */
/* $NetBSD: genfs_vnops.c,v 1.41 2001/11/30 15:18:39 christos Exp $ */
/*
* Copyright (c) 1982, 1986, 1989, 1993
@ -35,7 +35,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: genfs_vnops.c,v 1.40 2001/11/10 13:33:41 lukem Exp $");
__KERNEL_RCSID(0, "$NetBSD: genfs_vnops.c,v 1.41 2001/11/30 15:18:39 christos Exp $");
#include "opt_nfsserver.h"
@ -66,6 +66,8 @@ __KERNEL_RCSID(0, "$NetBSD: genfs_vnops.c,v 1.40 2001/11/10 13:33:41 lukem Exp $
#include <nfs/nfs_var.h>
#endif
#define MAX_READ_AHEAD 16 /* XXXUBC 16 */
int
genfs_poll(v)
void *v;
@ -464,7 +466,7 @@ genfs_getpages(v)
struct vnode *devvp;
struct genfs_node *gp = VTOG(vp);
struct uvm_object *uobj = &vp->v_uobj;
struct vm_page *pg, *pgs[16]; /* XXXUBC 16 */
struct vm_page *pg, *pgs[MAX_READ_AHEAD];
struct ucred *cred = curproc->p_ucred; /* XXXUBC curproc */
boolean_t async = (flags & PGO_SYNCIO) == 0;
boolean_t write = (ap->a_access_type & VM_PROT_WRITE) != 0;
@ -476,7 +478,7 @@ genfs_getpages(v)
vp, ap->a_offset >> 32, ap->a_offset, *ap->a_count);
/* XXXUBC temp limit */
if (*ap->a_count > 16) {
if (*ap->a_count > MAX_READ_AHEAD) {
panic("genfs_getpages: too many pages");
}
@ -851,15 +853,19 @@ loopdone:
raout:
if (!error && !async && !write && ((int)raoffset & 0xffff) == 0 &&
PAGE_SHIFT <= 16) {
off_t rasize;
int racount;
racount = 1 << (16 - PAGE_SHIFT);
/* XXXUBC temp limit, from above */
racount = MIN(1 << (16 - PAGE_SHIFT), MAX_READ_AHEAD);
rasize = racount << PAGE_SHIFT;
(void) VOP_GETPAGES(vp, raoffset, NULL, &racount, 0,
VM_PROT_READ, 0, 0);
simple_lock(&uobj->vmobjlock);
racount = 1 << (16 - PAGE_SHIFT);
(void) VOP_GETPAGES(vp, raoffset + 0x10000, NULL, &racount, 0,
/* XXXUBC temp limit, from above */
racount = MIN(1 << (16 - PAGE_SHIFT), MAX_READ_AHEAD);
(void) VOP_GETPAGES(vp, raoffset + rasize, NULL, &racount, 0,
VM_PROT_READ, 0, 0);
simple_lock(&uobj->vmobjlock);
}