Module Name: src
Committed By: ad
Date: Sun May 24 20:05:54 UTC 2020
Modified Files:
src/sys/uvm: uvm_bio.c
Log Message:
- 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.
To generate a diff of this commit:
cvs rdiff -u -r1.115 -r1.116 src/sys/uvm/uvm_bio.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/uvm/uvm_bio.c
diff -u src/sys/uvm/uvm_bio.c:1.115 src/sys/uvm/uvm_bio.c:1.116
--- src/sys/uvm/uvm_bio.c:1.115 Sat May 23 11:59:03 2020
+++ src/sys/uvm/uvm_bio.c Sun May 24 20:05:53 2020
@@ -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, str
*
* 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
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 *uo
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) {
