Commit 9b6c8c9b authored by NeilBrown's avatar NeilBrown Committed by Chuck Lever
Browse files

nfsd: make nfsd_stats.th_cnt atomic_t 



This allows us to move the updates for th_cnt out of the mutex.
This is a step towards reducing mutex coverage in nfsd().

Signed-off-by: default avatarNeilBrown <neilb@suse.de>
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
parent ec52361d

fs/nfsd/nfssvc.c

+3 −3
Original line number Diff line number Diff line
@@ -57,7 +57,7 @@ static __be32 nfsd_init_request(struct svc_rqst *, 
/*

 * nfsd_mutex protects nn->nfsd_serv -- both the pointer itself and the members

 * of the svc_serv struct. In particular, ->sv_nrthreads but also to some

 * extent ->sv_temp_socks and ->sv_permsocks. It also protects nfsdstats.th_cnt

 * extent ->sv_temp_socks and ->sv_permsocks.

 *

 * If (out side the lock) nn->nfsd_serv is non-NULL, then it must point to a

 * properly initialised 'struct svc_serv' with ->sv_nrthreads > 0 (unless
@@ -955,8 +955,8 @@ nfsd(void *vrqstp) 
	allow_signal(SIGINT);

	allow_signal(SIGQUIT);



	nfsdstats.th_cnt++;

	mutex_unlock(&nfsd_mutex);

	atomic_inc(&nfsdstats.th_cnt);



	set_freezable();
@@ -983,8 +983,8 @@ nfsd(void *vrqstp) 
	/* Clear signals before calling svc_exit_thread() */

	flush_signals(current);



	atomic_dec(&nfsdstats.th_cnt);

	mutex_lock(&nfsd_mutex);

	nfsdstats.th_cnt --;



out:

	/* Take an extra ref so that the svc_put in svc_exit_thread()

fs/nfsd/stats.c

+1 −1
Original line number Diff line number Diff line
@@ -45,7 +45,7 @@ static int nfsd_proc_show(struct seq_file *seq, void *v) 
		   percpu_counter_sum_positive(&nfsdstats.counter[NFSD_STATS_IO_WRITE]));



	/* thread usage: */

	seq_printf(seq, "th %u 0", nfsdstats.th_cnt);

	seq_printf(seq, "th %u 0", atomic_read(&nfsdstats.th_cnt));



	/* deprecated thread usage histogram stats */

	for (i = 0; i < 10; i++)

fs/nfsd/stats.h

+1 −3
Original line number Diff line number Diff line
@@ -29,11 +29,9 @@ enum { 
struct nfsd_stats {

	struct percpu_counter	counter[NFSD_STATS_COUNTERS_NUM];



	/* Protected by nfsd_mutex */

	unsigned int	th_cnt;		/* number of available threads */

	atomic_t	th_cnt;		/* number of available threads */

};





extern struct nfsd_stats	nfsdstats;



extern struct svc_stat		nfsd_svcstats;