| Message ID | 201307311532055128853@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Jul 31, 2013 at 3:32 PM, majianpeng <majianpeng@gmail.com> wrote: > > [snip] > Test case > A: touch file > dd if=file of=/dev/null bs=5M count=1 iflag=direct > B: [data(2M)|hole(2m)][data(2M)] > dd if=file of=/dev/null bs=8M count=1 iflag=direct > C: [data(4M)[hole(4M)][hole(4M)][data(2M)] > dd if=file of=/dev/null bs=16M count=1 iflag=direct > D: touch file;truncate -s 5M file > dd if=file of=/dev/null bs=8M count=1 iflag=direct > > Those cases can work. > Now i make different processing for short-read between 'ret > 0' and "ret =0". > For the short-read which ret > 0, it don't do read-page rather than zero the left area. > This means reduce one meaningless read operation. > This patch looks good. But I still hope not to duplicate code. how about change "hit_stripe = this_len < left;" to "hit_stripe = this_len < left && (ret == this_len || pos + this_len < inode->i_size);" > diff --git a/fs/ceph/file.c b/fs/ceph/file.c > index 2ddf061..f643ec8 100644 > --- a/fs/ceph/file.c > +++ b/fs/ceph/file.c > @@ -350,13 +350,17 @@ more: > ret, hit_stripe ? " HITSTRIPE" : "", was_short ? " SHORT" : ""); > > if (ret > 0) { changes this to "(ret >= 0)" > - int didpages = (page_align + ret) >> PAGE_CACHE_SHIFT; > - > - if (read < pos - off) { > diff --git a/fs/ceph/file.c b/fs/ceph/file.c > index 2ddf061..f643ec8 100644 > --- a/fs/ceph/file.c > +++ b/fs/ceph/file.c > @@ -350,13 +350,17 @@ more: > ret, hit_stripe ? " HITSTRIPE" : "", was_short ? " SHORT" : ""); > > if (ret > 0) { > - int didpages = (page_align + ret) >> PAGE_CACHE_SHIFT; > - > - if (read < pos - off) { > - dout(" zero gap %llu to %llu\n", off + read, pos); > - ceph_zero_page_vector_range(page_align + read, > - pos - off - read, pages); > + int didpages; > + > + if (was_short && pos + ret < inode->i_size) { change this to "(was_short && hit_stripe)" by this way, we can avoid modifying the "zero trailing bytes" code. Regards, Yan, Zheng > + u64 tmp = min(this_len - ret, > + inode->i_size - pos - ret); > + dout(" zero gap %llu to %llu\n", pos + ret, pos + ret + tmp); > + ceph_zero_page_vector_range(page_align + read + ret, > + tmp, pages); > + ret += tmp; > } > + didpages = (page_align + ret) >> PAGE_CACHE_SHIFT; > pos += ret; > read = pos - off; > left -= ret; > @@ -375,13 +379,25 @@ more: > > /* zero trailing bytes (inside i_size) */ > if (left > 0 && pos < inode->i_size) { > + int didpages; > if (pos + left > inode->i_size) > left = inode->i_size - pos; > > - dout("zero tail %d\n", left); > - ceph_zero_page_vector_range(page_align + read, left, > + ret = min(left, this_len); > + dout("zero tail %d\n", ret); > + ceph_zero_page_vector_range(page_align + read, ret, > pages); > - read += left; > + didpages = (page_align + ret) >> PAGE_CACHE_SHIFT; > + > + pos += ret; > + read = pos - off; > + left -= ret; > + page_pos += didpages; > + pages_left -= didpages; > + > + /* hit stripe? */ > + if (left && hit_stripe) > + goto more; > } > } > -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/ceph/file.c b/fs/ceph/file.c index 2ddf061..f643ec8 100644 --- a/fs/ceph/file.c +++ b/fs/ceph/file.c @@ -350,13 +350,17 @@ more: ret, hit_stripe ? " HITSTRIPE" : "", was_short ? " SHORT" : ""); if (ret > 0) { - int didpages = (page_align + ret) >> PAGE_CACHE_SHIFT; - - if (read < pos - off) { diff --git a/fs/ceph/file.c b/fs/ceph/file.c index 2ddf061..f643ec8 100644 --- a/fs/ceph/file.c +++ b/fs/ceph/file.c @@ -350,13 +350,17 @@ more: ret, hit_stripe ? " HITSTRIPE" : "", was_short ? " SHORT" : ""); if (ret > 0) { - int didpages = (page_align + ret) >> PAGE_CACHE_SHIFT; - - if (read < pos - off) { - dout(" zero gap %llu to %llu\n", off + read, pos); - ceph_zero_page_vector_range(page_align + read, - pos - off - read, pages); + int didpages; + + if (was_short && pos + ret < inode->i_size) { + u64 tmp = min(this_len - ret, + inode->i_size - pos - ret); + dout(" zero gap %llu to %llu\n", pos + ret, pos + ret + tmp); + ceph_zero_page_vector_range(page_align + read + ret,
[snip] Test case A: touch file dd if=file of=/dev/null bs=5M count=1 iflag=direct B: [data(2M)|hole(2m)][data(2M)] dd if=file of=/dev/null bs=8M count=1 iflag=direct C: [data(4M)[hole(4M)][hole(4M)][data(2M)] dd if=file of=/dev/null bs=16M count=1 iflag=direct D: touch file;truncate -s 5M file dd if=file of=/dev/null bs=8M count=1 iflag=direct Those cases can work. Now i make different processing for short-read between 'ret > 0' and "ret =0". For the short-read which ret > 0, it don't do read-page rather than zero the left area. This means reduce one meaningless read operation. + tmp, pages); + ret += tmp; } + didpages = (page_align + ret) >> PAGE_CACHE_SHIFT; pos += ret; read = pos - off; left -= ret; @@ -375,13 +379,25 @@ more: /* zero trailing bytes (inside i_size) */ if (left > 0 && pos < inode->i_size) { + int didpages; if (pos + left > inode->i_size) left = inode->i_size - pos; - dout("zero tail %d\n", left); - ceph_zero_page_vector_range(page_align + read, left, + ret = min(left, this_len); + dout("zero tail %d\n", ret); + ceph_zero_page_vector_range(page_align + read, ret, pages); - read += left; + didpages = (page_align + ret) >> PAGE_CACHE_SHIFT; + + pos += ret; + read = pos - off; + left -= ret; + page_pos += didpages; + pages_left -= didpages; + + /* hit stripe? */ + if (left && hit_stripe) + goto more; } }