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Reduce the amount of calls to VOP_BMAP() made from the local vnode

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pager.  It is enough to execute VOP_BMAP() once to obtain both the
disk block address for the requested page, and the before/after limits
for the contiguous run.  The clipping of the vm_page_t array passed to
the vnode_pager_generic_getpages() and the disk address for the first
page in the clipped array can be deduced from the call results.

While there, remove some noise (like if (1) {...}) and adjust nearby
code.

Reviewed by:	alc
Discussed with:	glebius
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	3 weeks
This commit is contained in:
Konstantin Belousov 2015-10-24 21:59:22 +00:00
parent af95bbf5bf
commit eac91e326a
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=289895
1 changed files with 39 additions and 81 deletions
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120
sys/vm/vnode_pager.c
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@ -767,26 +767,21 @@ vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *m, int bytecount,
int reqpage, vop_getpages_iodone_t iodone, void *arg)
{
vm_object_t object;
off_t foff;
int i, j, size, bsize, first, *freecnt;
daddr_t firstaddr, reqblock;
struct bufobj *bo;
int runpg;
int runend;
struct buf *bp;
int count;
int error;
object = vp->v_object;
count = bytecount / PAGE_SIZE;
daddr_t firstaddr, reqblock;
off_t foff;
int pbefore, pafter, i, size, bsize, first, last, *freecnt;
int count, error, before, after, secmask;
KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
("vnode_pager_generic_getpages does not support devices"));
if (vp->v_iflag & VI_DOOMED)
return VM_PAGER_BAD;
return (VM_PAGER_BAD);
object = vp->v_object;
count = bytecount / PAGE_SIZE;
bsize = vp->v_mount->mnt_stat.f_iosize;
foff = IDX_TO_OFF(m[reqpage]->pindex);
/*
* Synchronous and asynchronous paging operations use different
@ -805,7 +800,8 @@ vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *m, int bytecount,
* If the file system doesn't support VOP_BMAP, use old way of
* getting pages via VOP_READ.
*/
error = VOP_BMAP(vp, foff / bsize, &bo, &reqblock, NULL, NULL);
error = VOP_BMAP(vp, IDX_TO_OFF(m[reqpage]->pindex) / bsize, &bo,
&reqblock, &after, &before);
if (error == EOPNOTSUPP) {
relpbuf(bp, freecnt);
VM_OBJECT_WLOCK(object);
@ -836,7 +832,7 @@ vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *m, int bytecount,
vm_pager_free_nonreq(object, m, reqpage, count, FALSE);
PCPU_INC(cnt.v_vnodein);
PCPU_INC(cnt.v_vnodepgsin);
return vnode_pager_input_smlfs(object, m[reqpage]);
return (vnode_pager_input_smlfs(object, m[reqpage]));
}
/*
@ -870,75 +866,39 @@ vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *m, int bytecount,
VM_OBJECT_WUNLOCK(object);
}
/*
* here on direct device I/O
*/
firstaddr = -1;
/*
* calculate the run that includes the required page
*/
for (first = 0, i = 0; i < count; i = runend) {
if (vnode_pager_addr(vp, IDX_TO_OFF(m[i]->pindex), &firstaddr,
&runpg) != 0) {
relpbuf(bp, freecnt);
/* The requested page may be out of range. */
vm_pager_free_nonreq(object, m + i, reqpage - i,
count - i, FALSE);
return (VM_PAGER_ERROR);
}
if (firstaddr == -1) {
VM_OBJECT_WLOCK(object);
if (i == reqpage && foff < object->un_pager.vnp.vnp_size) {
panic("vnode_pager_getpages: unexpected missing page: firstaddr: %jd, foff: 0x%jx%08jx, vnp_size: 0x%jx%08jx",
(intmax_t)firstaddr, (uintmax_t)(foff >> 32),
(uintmax_t)foff,
(uintmax_t)
(object->un_pager.vnp.vnp_size >> 32),
(uintmax_t)object->un_pager.vnp.vnp_size);
}
pbefore = (daddr_t)before * bsize / PAGE_SIZE;
pafter = (daddr_t)after * bsize / PAGE_SIZE;
first = reqpage < pbefore ? 0 : reqpage - pbefore;
last = reqpage + pafter >= count ? count - 1 : reqpage + pafter;
if (first > 0 || last + 1 < count) {
VM_OBJECT_WLOCK(object);
for (i = 0; i < first; i++) {
vm_page_lock(m[i]);
vm_page_free(m[i]);
vm_page_unlock(m[i]);
VM_OBJECT_WUNLOCK(object);
runend = i + 1;
first = runend;
continue;
}
runend = i + runpg;
if (runend <= reqpage) {
VM_OBJECT_WLOCK(object);
for (j = i; j < runend; j++) {
vm_page_lock(m[j]);
vm_page_free(m[j]);
vm_page_unlock(m[j]);
}
VM_OBJECT_WUNLOCK(object);
} else {
if (runpg < (count - first)) {
VM_OBJECT_WLOCK(object);
for (i = first + runpg; i < count; i++) {
vm_page_lock(m[i]);
vm_page_free(m[i]);
vm_page_unlock(m[i]);
}
VM_OBJECT_WUNLOCK(object);
count = first + runpg;
}
break;
for (i = last + 1; i < count; i++) {
vm_page_lock(m[i]);
vm_page_free(m[i]);
vm_page_unlock(m[i]);
}
first = runend;
VM_OBJECT_WUNLOCK(object);
}
/*
* the first and last page have been calculated now, move input pages
* to be zero based...
* here on direct device I/O
*/
if (first != 0) {
m += first;
count -= first;
reqpage -= first;
}
firstaddr = reqblock;
firstaddr += (IDX_TO_OFF(m[reqpage]->pindex) % bsize) / DEV_BSIZE;
firstaddr -= IDX_TO_OFF(reqpage - first) / DEV_BSIZE;
/*
* The first and last page have been calculated now, move
* input pages to be zero based, and adjust the count.
*/
m += first;
reqpage -= first;
count = last - first + 1;
/*
* calculate the file virtual address for the transfer
@ -957,13 +917,11 @@ vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *m, int bytecount,
/*
* round up physical size for real devices.
*/
if (1) {
int secmask = bo->bo_bsize - 1;
KASSERT(secmask < PAGE_SIZE && secmask > 0,
("vnode_pager_generic_getpages: sector size %d too large",
secmask + 1));
size = (size + secmask) & ~secmask;
}
secmask = bo->bo_bsize - 1;
KASSERT(secmask < PAGE_SIZE && secmask > 0,
("vnode_pager_generic_getpages: sector size %d too large",
secmask + 1));
size = (size + secmask) & ~secmask;
/*
* and map the pages to be read into the kva, if the filesystem