svn commit: r271596 - in head/sys: fs/nfsclient nfsclient vm
Alan Cox
alc at FreeBSD.org
Sun Sep 14 18:07:57 UTC 2014
Author: alc
Date: Sun Sep 14 18:07:55 2014
New Revision: 271596
URL: http://svnweb.freebsd.org/changeset/base/271596
Log:
Avoid an exclusive acquisition of the object lock on the expected execution
path through the NFS clients' getpages functions.
Introduce vm_pager_free_nonreq(). This function can be used to eliminate
code that is duplicated in many getpages functions. Also, in contrast to
the code that currently appears in those getpages functions,
vm_pager_free_nonreq() avoids acquiring an exclusive object lock in one
case.
Reviewed by: kib
MFC after: 6 weeks
Sponsored by: EMC / Isilon Storage Division
Modified:
head/sys/fs/nfsclient/nfs_clbio.c
head/sys/nfsclient/nfs_bio.c
head/sys/vm/vm_pager.c
head/sys/vm/vm_pager.h
head/sys/vm/vnode_pager.c
Modified: head/sys/fs/nfsclient/nfs_clbio.c
==============================================================================
--- head/sys/fs/nfsclient/nfs_clbio.c Sun Sep 14 17:47:04 2014 (r271595)
+++ head/sys/fs/nfsclient/nfs_clbio.c Sun Sep 14 18:07:55 2014 (r271596)
@@ -129,23 +129,20 @@ ncl_getpages(struct vop_getpages_args *a
npages = btoc(count);
/*
+ * Since the caller has busied the requested page, that page's valid
+ * field will not be changed by other threads.
+ */
+ vm_page_assert_xbusied(pages[ap->a_reqpage]);
+
+ /*
* If the requested page is partially valid, just return it and
* allow the pager to zero-out the blanks. Partially valid pages
* can only occur at the file EOF.
*/
- VM_OBJECT_WLOCK(object);
if (pages[ap->a_reqpage]->valid != 0) {
- for (i = 0; i < npages; ++i) {
- if (i != ap->a_reqpage) {
- vm_page_lock(pages[i]);
- vm_page_free(pages[i]);
- vm_page_unlock(pages[i]);
- }
- }
- VM_OBJECT_WUNLOCK(object);
- return (0);
+ vm_pager_free_nonreq(object, pages, ap->a_reqpage, npages);
+ return (VM_PAGER_OK);
}
- VM_OBJECT_WUNLOCK(object);
/*
* We use only the kva address for the buffer, but this is extremely
@@ -175,15 +172,7 @@ ncl_getpages(struct vop_getpages_args *a
if (error && (uio.uio_resid == count)) {
ncl_printf("nfs_getpages: error %d\n", error);
- VM_OBJECT_WLOCK(object);
- for (i = 0; i < npages; ++i) {
- if (i != ap->a_reqpage) {
- vm_page_lock(pages[i]);
- vm_page_free(pages[i]);
- vm_page_unlock(pages[i]);
- }
- }
- VM_OBJECT_WUNLOCK(object);
+ vm_pager_free_nonreq(object, pages, ap->a_reqpage, npages);
return (VM_PAGER_ERROR);
}
Modified: head/sys/nfsclient/nfs_bio.c
==============================================================================
--- head/sys/nfsclient/nfs_bio.c Sun Sep 14 17:47:04 2014 (r271595)
+++ head/sys/nfsclient/nfs_bio.c Sun Sep 14 18:07:55 2014 (r271596)
@@ -123,23 +123,20 @@ nfs_getpages(struct vop_getpages_args *a
npages = btoc(count);
/*
+ * Since the caller has busied the requested page, that page's valid
+ * field will not be changed by other threads.
+ */
+ vm_page_assert_xbusied(pages[ap->a_reqpage]);
+
+ /*
* If the requested page is partially valid, just return it and
* allow the pager to zero-out the blanks. Partially valid pages
* can only occur at the file EOF.
*/
- VM_OBJECT_WLOCK(object);
if (pages[ap->a_reqpage]->valid != 0) {
- for (i = 0; i < npages; ++i) {
- if (i != ap->a_reqpage) {
- vm_page_lock(pages[i]);
- vm_page_free(pages[i]);
- vm_page_unlock(pages[i]);
- }
- }
- VM_OBJECT_WUNLOCK(object);
- return (0);
+ vm_pager_free_nonreq(object, pages, ap->a_reqpage, npages);
+ return (VM_PAGER_OK);
}
- VM_OBJECT_WUNLOCK(object);
/*
* We use only the kva address for the buffer, but this is extremely
@@ -169,15 +166,7 @@ nfs_getpages(struct vop_getpages_args *a
if (error && (uio.uio_resid == count)) {
nfs_printf("nfs_getpages: error %d\n", error);
- VM_OBJECT_WLOCK(object);
- for (i = 0; i < npages; ++i) {
- if (i != ap->a_reqpage) {
- vm_page_lock(pages[i]);
- vm_page_free(pages[i]);
- vm_page_unlock(pages[i]);
- }
- }
- VM_OBJECT_WUNLOCK(object);
+ vm_pager_free_nonreq(object, pages, ap->a_reqpage, npages);
return (VM_PAGER_ERROR);
}
Modified: head/sys/vm/vm_pager.c
==============================================================================
--- head/sys/vm/vm_pager.c Sun Sep 14 17:47:04 2014 (r271595)
+++ head/sys/vm/vm_pager.c Sun Sep 14 18:07:55 2014 (r271596)
@@ -282,6 +282,33 @@ vm_pager_object_lookup(struct pagerlst *
}
/*
+ * Free the non-requested pages from the given array.
+ */
+void
+vm_pager_free_nonreq(vm_object_t object, vm_page_t ma[], int reqpage,
+ int npages)
+{
+ int i;
+ boolean_t object_locked;
+
+ VM_OBJECT_ASSERT_UNLOCKED(object);
+ object_locked = FALSE;
+ for (i = 0; i < npages; ++i) {
+ if (i != reqpage) {
+ if (!object_locked) {
+ VM_OBJECT_WLOCK(object);
+ object_locked = TRUE;
+ }
+ vm_page_lock(ma[i]);
+ vm_page_free(ma[i]);
+ vm_page_unlock(ma[i]);
+ }
+ }
+ if (object_locked)
+ VM_OBJECT_WUNLOCK(object);
+}
+
+/*
* initialize a physical buffer
*/
Modified: head/sys/vm/vm_pager.h
==============================================================================
--- head/sys/vm/vm_pager.h Sun Sep 14 17:47:04 2014 (r271595)
+++ head/sys/vm/vm_pager.h Sun Sep 14 18:07:55 2014 (r271596)
@@ -106,6 +106,8 @@ static __inline int vm_pager_get_pages(v
static __inline boolean_t vm_pager_has_page(vm_object_t, vm_pindex_t, int *, int *);
void vm_pager_init(void);
vm_object_t vm_pager_object_lookup(struct pagerlst *, void *);
+void vm_pager_free_nonreq(vm_object_t object, vm_page_t ma[], int reqpage,
+ int npages);
/*
* vm_page_get_pages:
Modified: head/sys/vm/vnode_pager.c
==============================================================================
--- head/sys/vm/vnode_pager.c Sun Sep 14 17:47:04 2014 (r271595)
+++ head/sys/vm/vnode_pager.c Sun Sep 14 18:07:55 2014 (r271596)
@@ -722,14 +722,7 @@ vnode_pager_generic_getpages(struct vnod
VM_OBJECT_WUNLOCK(object);
return (error);
} else if (error != 0) {
- VM_OBJECT_WLOCK(object);
- for (i = 0; i < count; i++)
- if (i != reqpage) {
- vm_page_lock(m[i]);
- vm_page_free(m[i]);
- vm_page_unlock(m[i]);
- }
- VM_OBJECT_WUNLOCK(object);
+ vm_pager_free_nonreq(object, m, reqpage, count);
return (VM_PAGER_ERROR);
/*
@@ -739,14 +732,7 @@ vnode_pager_generic_getpages(struct vnod
*/
} else if ((PAGE_SIZE / bsize) > 1 &&
(vp->v_mount->mnt_stat.f_type != nfs_mount_type)) {
- VM_OBJECT_WLOCK(object);
- for (i = 0; i < count; i++)
- if (i != reqpage) {
- vm_page_lock(m[i]);
- vm_page_free(m[i]);
- vm_page_unlock(m[i]);
- }
- VM_OBJECT_WUNLOCK(object);
+ vm_pager_free_nonreq(object, m, reqpage, count);
PCPU_INC(cnt.v_vnodein);
PCPU_INC(cnt.v_vnodepgsin);
return vnode_pager_input_smlfs(object, m[reqpage]);
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