Home » Mailing lists » Devel » [PATCH v2 00/11] fuse: optimize scatter-gather direct IO
| [PATCH 11/11] fuse: optimize __fuse_direct_io() [message #47959 is a reply to message #47948] |
Wed, 19 September 2012 16:33   |
Maxim Patlasov
Messages: 45
Registered: July 2012
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Member |
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__fuse_direct_io() allocates fuse-requests by calling fuse_get_req(fc, n). The
patch calculates 'n' based on iov[] array. This is useful because allocating
FUSE_MAX_PAGES_PER_REQ page pointers and descriptors for each fuse request
would be waste of memory in case of iov-s of smaller size.
Signed-off-by: Maxim Patlasov <mpatlasov@parallels.com>
---
fs/fuse/file.c | 27 +++++++++++++++++++++++----
1 files changed, 23 insertions(+), 4 deletions(-)
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 5b0fa5d..5ecab19 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1090,14 +1090,14 @@ static int fuse_get_user_pages(struct fuse_req *req,
return 0;
}
- while (nbytes < *nbytesp && req->num_pages < FUSE_MAX_PAGES_PER_REQ) {
+ while (nbytes < *nbytesp && req->num_pages < req->max_pages) {
int npages;
unsigned long user_addr = fuse_get_ua(*iov_pp, *iov_offset_p);
unsigned offset = user_addr & ~PAGE_MASK;
size_t frag_size = fuse_get_fr_sz(*iov_pp, *iov_offset_p,
*nbytesp - nbytes);
- int n = FUSE_MAX_PAGES_PER_REQ - req->num_pages;
+ int n = req->max_pages - req->num_pages;
frag_size = min_t(size_t, frag_size, n << PAGE_SHIFT);
npages = (frag_size + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
@@ -1138,6 +1138,24 @@ static int fuse_get_user_pages(struct fuse_req *req,
return 0;
}
+static inline int fuse_iov_npages(const struct iovec *iov,
+ unsigned long nr_segs, size_t iov_offset)
+{
+ int npages = 0;
+
+ while (nr_segs-- > 0 && npages < FUSE_MAX_PAGES_PER_REQ) {
+ unsigned long user_addr = fuse_get_ua(iov, iov_offset);
+ unsigned offset = user_addr & ~PAGE_MASK;
+ size_t frag_size = iov->iov_len - iov_offset;
+
+ npages += (frag_size + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ iov++;
+ iov_offset = 0;
+ }
+
+ return min(npages, FUSE_MAX_PAGES_PER_REQ);
+}
+
static ssize_t __fuse_direct_io(struct file *file, const struct iovec *iov,
unsigned long nr_segs, size_t count,
loff_t *ppos, int write)
@@ -1150,7 +1168,7 @@ static ssize_t __fuse_direct_io(struct file *file, const struct iovec *iov,
struct fuse_req *req;
size_t iov_offset = 0;
- req = fuse_get_req(fc, FUSE_MAX_PAGES_PER_REQ);
+ req = fuse_get_req(fc, fuse_iov_npages(iov, nr_segs, iov_offset));
if (IS_ERR(req))
return PTR_ERR(req);
@@ -1186,7 +1204,8 @@ static ssize_t __fuse_direct_io(struct file *file, const struct iovec *iov,
break;
if (count) {
fuse_put_request(fc, req);
- req = fuse_get_req(fc, FUSE_MAX_PAGES_PER_REQ);
+ req = fuse_get_req(fc,
+ fuse_iov_npages(iov, nr_segs, iov_offset));
if (IS_ERR(req))
break;
}
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