Message ID | 1661886865-30304-2-git-send-email-dai.ngo@oracle.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | NFSD: memory shrinker for NFSv4 clients | expand |
On Tue, 2022-08-30 at 12:14 -0700, Dai Ngo wrote: > Add counter nfs4_courtesy_client_count to nfsd_net to keep track > of the number of courtesy clients in the system. > > Signed-off-by: Dai Ngo <dai.ngo@oracle.com> > --- > fs/nfsd/netns.h | 2 ++ > fs/nfsd/nfs4state.c | 14 +++++++++++--- > 2 files changed, 13 insertions(+), 3 deletions(-) > > diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h > index ffe17743cc74..2695dff1378a 100644 > --- a/fs/nfsd/netns.h > +++ b/fs/nfsd/netns.h > @@ -192,6 +192,8 @@ struct nfsd_net { > > atomic_t nfs4_client_count; > int nfs4_max_clients; > + > + atomic_t nfsd_courtesy_client_count; > }; > > /* Simple check to find out if a given net was properly initialized */ > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c > index c5d199d7e6b4..9675b5d8f408 100644 > --- a/fs/nfsd/nfs4state.c > +++ b/fs/nfsd/nfs4state.c > @@ -169,7 +169,8 @@ static __be32 get_client_locked(struct nfs4_client *clp) > if (is_client_expired(clp)) > return nfserr_expired; > atomic_inc(&clp->cl_rpc_users); > - clp->cl_state = NFSD4_ACTIVE; > + if (xchg(&clp->cl_state, NFSD4_ACTIVE) != NFSD4_ACTIVE) > + atomic_add_unless(&nn->nfsd_courtesy_client_count, -1, 0); I'd prefer this: if (clp->cl_state != NFSD4_ACTIVE) atomic_add_unless(... clp->cl_state = NFSD4_ACTIVE; It's more lines, but it's easier to read. It's may also be more efficient since you're protected by a spinlock anyway. I think it's also less deceptive when reading the code. When I see xchg() operations being used like that, my immediate thought is that they must be needed for synchronization purposes. It's not in this case. > return nfs_ok; > } > > @@ -190,7 +191,8 @@ renew_client_locked(struct nfs4_client *clp) > > list_move_tail(&clp->cl_lru, &nn->client_lru); > clp->cl_time = ktime_get_boottime_seconds(); > - clp->cl_state = NFSD4_ACTIVE; > + if (xchg(&clp->cl_state, NFSD4_ACTIVE) != NFSD4_ACTIVE) > + atomic_add_unless(&nn->nfsd_courtesy_client_count, -1, 0); > } > > static void put_client_renew_locked(struct nfs4_client *clp) > @@ -2233,6 +2235,8 @@ __destroy_client(struct nfs4_client *clp) > if (clp->cl_cb_conn.cb_xprt) > svc_xprt_put(clp->cl_cb_conn.cb_xprt); > atomic_add_unless(&nn->nfs4_client_count, -1, 0); > + if (clp->cl_state != NFSD4_ACTIVE) > + atomic_add_unless(&nn->nfsd_courtesy_client_count, -1, 0); > free_client(clp); > wake_up_all(&expiry_wq); > } > @@ -4356,6 +4360,8 @@ void nfsd4_init_leases_net(struct nfsd_net *nn) > max_clients = (u64)si.totalram * si.mem_unit / (1024 * 1024 * 1024); > max_clients *= NFS4_CLIENTS_PER_GB; > nn->nfs4_max_clients = max_t(int, max_clients, NFS4_CLIENTS_PER_GB); > + > + atomic_set(&nn->nfsd_courtesy_client_count, 0); > } > > static void init_nfs4_replay(struct nfs4_replay *rp) > @@ -5879,7 +5885,9 @@ nfs4_get_client_reaplist(struct nfsd_net *nn, struct list_head *reaplist, > if (!state_expired(lt, clp->cl_time)) > break; > if (!atomic_read(&clp->cl_rpc_users)) > - clp->cl_state = NFSD4_COURTESY; > + if (xchg(&clp->cl_state, NFSD4_COURTESY) == > + NFSD4_ACTIVE) > + atomic_inc(&nn->nfsd_courtesy_client_count); > if (!client_has_state(clp)) > goto exp_client; > if (!nfs4_anylock_blockers(clp))
> On Aug 30, 2022, at 3:40 PM, Jeff Layton <jlayton@kernel.org> wrote: > > On Tue, 2022-08-30 at 12:14 -0700, Dai Ngo wrote: >> Add counter nfs4_courtesy_client_count to nfsd_net to keep track >> of the number of courtesy clients in the system. >> >> Signed-off-by: Dai Ngo <dai.ngo@oracle.com> >> --- >> fs/nfsd/netns.h | 2 ++ >> fs/nfsd/nfs4state.c | 14 +++++++++++--- >> 2 files changed, 13 insertions(+), 3 deletions(-) >> >> diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h >> index ffe17743cc74..2695dff1378a 100644 >> --- a/fs/nfsd/netns.h >> +++ b/fs/nfsd/netns.h >> @@ -192,6 +192,8 @@ struct nfsd_net { >> >> atomic_t nfs4_client_count; >> int nfs4_max_clients; >> + >> + atomic_t nfsd_courtesy_client_count; >> }; >> >> /* Simple check to find out if a given net was properly initialized */ >> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c >> index c5d199d7e6b4..9675b5d8f408 100644 >> --- a/fs/nfsd/nfs4state.c >> +++ b/fs/nfsd/nfs4state.c >> @@ -169,7 +169,8 @@ static __be32 get_client_locked(struct nfs4_client *clp) >> if (is_client_expired(clp)) >> return nfserr_expired; >> atomic_inc(&clp->cl_rpc_users); >> - clp->cl_state = NFSD4_ACTIVE; >> + if (xchg(&clp->cl_state, NFSD4_ACTIVE) != NFSD4_ACTIVE) >> + atomic_add_unless(&nn->nfsd_courtesy_client_count, -1, 0); > > I'd prefer this: > > if (clp->cl_state != NFSD4_ACTIVE) > atomic_add_unless(... > clp->cl_state = NFSD4_ACTIVE; > > It's more lines, but it's easier to read. It's may also be more > efficient since you're protected by a spinlock anyway. > > I think it's also less deceptive when reading the code. When I see > xchg() operations being used like that, my immediate thought is that > they must be needed for synchronization purposes. It's not in this case. Agree: generally speaking, primitives like xchg() are used only when hardware-assisted synchronization is needed. These are expensive operations, to be used sparingly. Let's replace these with plain vanilla "=", as Jeff suggested. Likewise, I'm not totally convinced that nfsd_courtesy_client_count has to be an atomic. >> return nfs_ok; >> } >> >> @@ -190,7 +191,8 @@ renew_client_locked(struct nfs4_client *clp) >> >> list_move_tail(&clp->cl_lru, &nn->client_lru); >> clp->cl_time = ktime_get_boottime_seconds(); >> - clp->cl_state = NFSD4_ACTIVE; >> + if (xchg(&clp->cl_state, NFSD4_ACTIVE) != NFSD4_ACTIVE) >> + atomic_add_unless(&nn->nfsd_courtesy_client_count, -1, 0); >> } >> >> static void put_client_renew_locked(struct nfs4_client *clp) >> @@ -2233,6 +2235,8 @@ __destroy_client(struct nfs4_client *clp) >> if (clp->cl_cb_conn.cb_xprt) >> svc_xprt_put(clp->cl_cb_conn.cb_xprt); >> atomic_add_unless(&nn->nfs4_client_count, -1, 0); >> + if (clp->cl_state != NFSD4_ACTIVE) >> + atomic_add_unless(&nn->nfsd_courtesy_client_count, -1, 0); >> free_client(clp); >> wake_up_all(&expiry_wq); >> } >> @@ -4356,6 +4360,8 @@ void nfsd4_init_leases_net(struct nfsd_net *nn) >> max_clients = (u64)si.totalram * si.mem_unit / (1024 * 1024 * 1024); >> max_clients *= NFS4_CLIENTS_PER_GB; >> nn->nfs4_max_clients = max_t(int, max_clients, NFS4_CLIENTS_PER_GB); >> + >> + atomic_set(&nn->nfsd_courtesy_client_count, 0); >> } >> >> static void init_nfs4_replay(struct nfs4_replay *rp) >> @@ -5879,7 +5885,9 @@ nfs4_get_client_reaplist(struct nfsd_net *nn, struct list_head *reaplist, >> if (!state_expired(lt, clp->cl_time)) >> break; >> if (!atomic_read(&clp->cl_rpc_users)) >> - clp->cl_state = NFSD4_COURTESY; >> + if (xchg(&clp->cl_state, NFSD4_COURTESY) == >> + NFSD4_ACTIVE) >> + atomic_inc(&nn->nfsd_courtesy_client_count); >> if (!client_has_state(clp)) >> goto exp_client; >> if (!nfs4_anylock_blockers(clp)) > > -- > Jeff Layton <jlayton@kernel.org> -- Chuck Lever
diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h index ffe17743cc74..2695dff1378a 100644 --- a/fs/nfsd/netns.h +++ b/fs/nfsd/netns.h @@ -192,6 +192,8 @@ struct nfsd_net { atomic_t nfs4_client_count; int nfs4_max_clients; + + atomic_t nfsd_courtesy_client_count; }; /* Simple check to find out if a given net was properly initialized */ diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index c5d199d7e6b4..9675b5d8f408 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -169,7 +169,8 @@ static __be32 get_client_locked(struct nfs4_client *clp) if (is_client_expired(clp)) return nfserr_expired; atomic_inc(&clp->cl_rpc_users); - clp->cl_state = NFSD4_ACTIVE; + if (xchg(&clp->cl_state, NFSD4_ACTIVE) != NFSD4_ACTIVE) + atomic_add_unless(&nn->nfsd_courtesy_client_count, -1, 0); return nfs_ok; } @@ -190,7 +191,8 @@ renew_client_locked(struct nfs4_client *clp) list_move_tail(&clp->cl_lru, &nn->client_lru); clp->cl_time = ktime_get_boottime_seconds(); - clp->cl_state = NFSD4_ACTIVE; + if (xchg(&clp->cl_state, NFSD4_ACTIVE) != NFSD4_ACTIVE) + atomic_add_unless(&nn->nfsd_courtesy_client_count, -1, 0); } static void put_client_renew_locked(struct nfs4_client *clp) @@ -2233,6 +2235,8 @@ __destroy_client(struct nfs4_client *clp) if (clp->cl_cb_conn.cb_xprt) svc_xprt_put(clp->cl_cb_conn.cb_xprt); atomic_add_unless(&nn->nfs4_client_count, -1, 0); + if (clp->cl_state != NFSD4_ACTIVE) + atomic_add_unless(&nn->nfsd_courtesy_client_count, -1, 0); free_client(clp); wake_up_all(&expiry_wq); } @@ -4356,6 +4360,8 @@ void nfsd4_init_leases_net(struct nfsd_net *nn) max_clients = (u64)si.totalram * si.mem_unit / (1024 * 1024 * 1024); max_clients *= NFS4_CLIENTS_PER_GB; nn->nfs4_max_clients = max_t(int, max_clients, NFS4_CLIENTS_PER_GB); + + atomic_set(&nn->nfsd_courtesy_client_count, 0); } static void init_nfs4_replay(struct nfs4_replay *rp) @@ -5879,7 +5885,9 @@ nfs4_get_client_reaplist(struct nfsd_net *nn, struct list_head *reaplist, if (!state_expired(lt, clp->cl_time)) break; if (!atomic_read(&clp->cl_rpc_users)) - clp->cl_state = NFSD4_COURTESY; + if (xchg(&clp->cl_state, NFSD4_COURTESY) == + NFSD4_ACTIVE) + atomic_inc(&nn->nfsd_courtesy_client_count); if (!client_has_state(clp)) goto exp_client; if (!nfs4_anylock_blockers(clp))
Add counter nfs4_courtesy_client_count to nfsd_net to keep track of the number of courtesy clients in the system. Signed-off-by: Dai Ngo <dai.ngo@oracle.com> --- fs/nfsd/netns.h | 2 ++ fs/nfsd/nfs4state.c | 14 +++++++++++--- 2 files changed, 13 insertions(+), 3 deletions(-)