| Message ID | 20220215122316.7625-1-xiubli@redhat.com |
|---|---|
| Headers | show |
| Series | ceph: fix cephfs rsync kworker high load issue | expand |
xiubli@redhat.com writes: > From: Xiubo Li <xiubli@redhat.com> > > There could be huge number of capsnap queued in a short time, on > x86_64 it's 248 bytes, which will be rounded up to 256 bytes by > kzalloc. Move this to a dedicated slabcache to save 8 bytes for > each. > > For the kmalloc-256 slab cache, the actual size will be 512 bytes: > kmalloc-256 21797 74656 512 32 4 : tunables, etc > > For a dedicated slab cache the real size is 312 bytes: > ceph_cap_snap 0 0 312 52 4 : tunables, etc > > So actually we can save 200 bytes for each. > > Signed-off-by: Xiubo Li <xiubli@redhat.com> > --- > fs/ceph/snap.c | 5 +++-- > fs/ceph/super.c | 7 +++++++ > fs/ceph/super.h | 2 +- > include/linux/ceph/libceph.h | 1 + > 4 files changed, 12 insertions(+), 3 deletions(-) > > diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c > index b41e6724c591..c787775eaf2a 100644 > --- a/fs/ceph/snap.c > +++ b/fs/ceph/snap.c > @@ -482,7 +482,7 @@ static void ceph_queue_cap_snap(struct ceph_inode_info *ci) > struct ceph_buffer *old_blob = NULL; > int used, dirty; > > - capsnap = kzalloc(sizeof(*capsnap), GFP_NOFS); > + capsnap = kmem_cache_alloc(ceph_cap_snap_cachep, GFP_NOFS); Unfortunately, this is causing issues in my testing. Looks like there are several fields that are assumed to be initialised to zero. I've seen two BUGs so far, in functions ceph_try_drop_cap_snap (capsnap->cap_flush.tid > 0) and __ceph_finish_cap_snap (capsnap->writing). I guess you'll have to either zero out all that memory, or manually initialise the fields (not sure which ones really require that). Cheers,
From: Xiubo Li <xiubli@redhat.com> Xiubo Li (3): ceph: move to a dedicated slabcache for ceph_cap_snap ceph: move kzalloc under i_ceph_lock with GFP_ATOMIC flag ceph: do no update snapshot context when there is no new snapshot fs/ceph/snap.c | 56 ++++++++++++++++++++++++------------ fs/ceph/super.c | 7 +++++ fs/ceph/super.h | 2 +- include/linux/ceph/libceph.h | 1 + 4 files changed, 47 insertions(+), 19 deletions(-)