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- ubc_uiomove(): Always use direct access in the UBC_FAULTBUSY case, since 

it works basically the same way as !direct minus temporary mappings, and
  there are no concurrency issues.

- ubc_alloc_direct(): In the PGO_OVERWRITE case blocks are allocated
  beforehand.  Avoid waking or activating pages unless needed.
This commit is contained in:
ad 2020-05-24 20:05:53 +00:00
parent 0f8b984644
commit 504f478a85
1 changed files with 20 additions and 10 deletions
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30
sys/uvm/uvm_bio.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: uvm_bio.c,v 1.115 2020/05/23 11:59:03 ad Exp $ */
/* $NetBSD: uvm_bio.c,v 1.116 2020/05/24 20:05:53 ad Exp $ */
/*
* Copyright (c) 1998 Chuck Silvers.
@ -34,7 +34,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: uvm_bio.c,v 1.115 2020/05/23 11:59:03 ad Exp $");
__KERNEL_RCSID(0, "$NetBSD: uvm_bio.c,v 1.116 2020/05/24 20:05:53 ad Exp $");
#include "opt_uvmhist.h"
#include "opt_ubc.h"
@ -748,9 +748,13 @@ ubc_uiomove(struct uvm_object *uobj, struct uio *uio, vsize_t todo, int advice,
*
* avoid the problem by disallowing direct access if the object
* might be visible somewhere via mmap().
*
* XXX concurrent reads cause thundering herd issues with PG_BUSY.
* In the future enable by default for writes or if ncpu<=2, and
* make the toggle override that.
*/
if (ubc_direct && (flags & UBC_ISMAPPED) == 0) {
if ((ubc_direct && (flags & UBC_ISMAPPED) == 0) ||
(flags & UBC_FAULTBUSY) != 0) {
return ubc_uiomove_direct(uobj, uio, todo, advice, flags);
}
#endif
@ -841,7 +845,7 @@ ubc_alloc_direct(struct uvm_object *uobj, voff_t offset, vsize_t *lenp,
if (flags & UBC_WRITE) {
if (flags & UBC_FAULTBUSY)
gpflags |= PGO_OVERWRITE;
gpflags |= PGO_OVERWRITE | PGO_NOBLOCKALLOC;
#if 0
KASSERT(!UVM_OBJ_NEEDS_WRITEFAULT(uobj));
#endif
@ -902,7 +906,10 @@ again:
/* Page must be writable by now */
KASSERT((pg->flags & PG_RDONLY) == 0 || (flags & UBC_WRITE) == 0);
/* No managed mapping - mark the page dirty. */
/*
* XXX For aobj pages. No managed mapping - mark the page
* dirty.
*/
if ((flags & UBC_WRITE) != 0) {
uvm_pagemarkdirty(pg, UVM_PAGE_STATUS_DIRTY);
}
@ -927,10 +934,13 @@ ubc_direct_release(struct uvm_object *uobj,
uvm_pagefree(pg);
continue;
}
uvm_pagelock(pg);
uvm_pageactivate(pg);
uvm_pagewakeup(pg);
uvm_pageunlock(pg);
if (uvm_pagewanted_p(pg) || uvmpdpol_pageactivate_p(pg)) {
uvm_pagelock(pg);
uvm_pageactivate(pg);
uvm_pagewakeup(pg);
uvm_pageunlock(pg);
}
/* Page was changed, no longer fake and neither clean. */
if (flags & UBC_WRITE) {