| Message ID | 1304803784-23756-2-git-send-email-slyfox@gentoo.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 05/07/2011 05:29 PM, slyich@gmail.com wrote: > Observed as a large delay when --mixed filesystem is filled up. > Test example: > 1. create tiny --mixed FS: > $ dd if=/dev/zero of=2G.img seek=$((2048 * 1024 * 1024 - 1)) count=1 bs=1 > $ mkfs.btrfs --mixed 2G.img > $ mount -oloop 2G.img /mnt/ut/ > 2. Try to fill it up: > $ dd if=/dev/urandom of=10M.file bs=10240 count=1024 > $ seq 1 256 | while read file_no; do echo $file_no; time cp 10M.file ${file_no}.copy; done > > Up to '200.copy' it goes fast, but when disk fills-up each -ENOSPC > message takes 3 seconds to pop-up _every_ ENOSPC (and in usermode linux > it's even more: 30-60 seconds!). (Maybe, time depends on kernel's timer resolution). > > No IO, no CPU load, just rescheduling. Some debugging revealed busy spinning > in shrink_delalloc. > > Signed-off-by: Sergei Trofimovich<slyfox@gentoo.org> > --- > fs/btrfs/extent-tree.c | 4 ++++ > 1 files changed, 4 insertions(+), 0 deletions(-) > > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c > index 9ee6bd5..9f5fdd3 100644 > --- a/fs/btrfs/extent-tree.c > +++ b/fs/btrfs/extent-tree.c > @@ -3425,6 +3425,10 @@ static int shrink_delalloc(struct btrfs_trans_handle *trans, > if (reserved == 0) > return 0; > > + /* nothing to shrink - nothing to reclaim */ > + if (root->fs_info->delalloc_bytes == 0) > + return 0; > + > max_reclaim = min(reserved, to_reclaim); > > while (loops< 1024) { Nice catch, you can add Reviewed-by: Josef Bacik <josef@redhat.com> Thanks, Josef -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, 09 May 2011 12:00:28 -0400 Josef Bacik <josef@redhat.com> wrote: > On 05/07/2011 05:29 PM, slyich@gmail.com wrote: > > Observed as a large delay when --mixed filesystem is filled up. > > Test example: > > 1. create tiny --mixed FS: > > $ dd if=/dev/zero of=2G.img seek=$((2048 * 1024 * 1024 - 1)) count=1 bs=1 > > $ mkfs.btrfs --mixed 2G.img > > $ mount -oloop 2G.img /mnt/ut/ > > 2. Try to fill it up: > > $ dd if=/dev/urandom of=10M.file bs=10240 count=1024 > > $ seq 1 256 | while read file_no; do echo $file_no; time cp 10M.file ${file_no}.copy; done > > > > Up to '200.copy' it goes fast, but when disk fills-up each -ENOSPC > > message takes 3 seconds to pop-up _every_ ENOSPC (and in usermode linux > > it's even more: 30-60 seconds!). (Maybe, time depends on kernel's timer resolution). > > > > No IO, no CPU load, just rescheduling. Some debugging revealed busy spinning > > in shrink_delalloc. > > > > Signed-off-by: Sergei Trofimovich<slyfox@gentoo.org> > > --- > > fs/btrfs/extent-tree.c | 4 ++++ > > 1 files changed, 4 insertions(+), 0 deletions(-) > > > > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c > > index 9ee6bd5..9f5fdd3 100644 > > --- a/fs/btrfs/extent-tree.c > > +++ b/fs/btrfs/extent-tree.c > > @@ -3425,6 +3425,10 @@ static int shrink_delalloc(struct btrfs_trans_handle *trans, > > if (reserved == 0) > > return 0; > > > > + /* nothing to shrink - nothing to reclaim */ > > + if (root->fs_info->delalloc_bytes == 0) > > + return 0; > > + > > max_reclaim = min(reserved, to_reclaim); > > > > while (loops< 1024) { > > Nice catch, you can add > > Reviewed-by: Josef Bacik <josef@redhat.com> Will add it (and fix patch enumeration) and resend. Thanks for the review!
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 9ee6bd5..9f5fdd3 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -3425,6 +3425,10 @@ static int shrink_delalloc(struct btrfs_trans_handle *trans, if (reserved == 0) return 0; + /* nothing to shrink - nothing to reclaim */ + if (root->fs_info->delalloc_bytes == 0) + return 0; + max_reclaim = min(reserved, to_reclaim); while (loops < 1024) {
Observed as a large delay when --mixed filesystem is filled up. Test example: 1. create tiny --mixed FS: $ dd if=/dev/zero of=2G.img seek=$((2048 * 1024 * 1024 - 1)) count=1 bs=1 $ mkfs.btrfs --mixed 2G.img $ mount -oloop 2G.img /mnt/ut/ 2. Try to fill it up: $ dd if=/dev/urandom of=10M.file bs=10240 count=1024 $ seq 1 256 | while read file_no; do echo $file_no; time cp 10M.file ${file_no}.copy; done Up to '200.copy' it goes fast, but when disk fills-up each -ENOSPC message takes 3 seconds to pop-up _every_ ENOSPC (and in usermode linux it's even more: 30-60 seconds!). (Maybe, time depends on kernel's timer resolution). No IO, no CPU load, just rescheduling. Some debugging revealed busy spinning in shrink_delalloc. Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org> --- fs/btrfs/extent-tree.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-)