archives/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-03-08 04:04:43 +01:00
Code Issues Projects Releases Packages Wiki Activity Actions

nfsd: adjust number of running nfsd threads based on activity

Browse source 
nfsd() is changed to pass a timeout to svc_recv() when there is a min
number of threads set, and to handle error returns from it:

In the case of -ETIMEDOUT, if the service mutex can be taken (via
trylock), the thread becomes an RQ_VICTIM so that it will exit,
providing that the actual number of threads is above pool->sp_nrthrmin.

In the case of -EBUSY, if the actual number of threads is below
pool->sp_nrthrmax, it will attempt to start a new thread. This attempt
is gated on a new SP_TASK_STARTING pool flag that serializes thread
creation attempts within a pool, and further by mutex_trylock().

Neil says: "I think we want memory pressure to be able to push a thread
into returning -ETIMEDOUT.  That can come later."

Signed-off-by: NeilBrown <neil@brown.name>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Jeff Layton 2026-01-06 13:59:49 -05:00 • committed by Chuck Lever
parent a0022a38be
commit 1c87a0c39a
2 changed files with 77 additions and 1 deletions
Download patch file Download diff file Expand all files Collapse all files

43
fs/nfsd/nfssvc.c
View file

@ -882,9 +882,11 @@ static int
nfsd(void *vrqstp)
{
struct svc_rqst *rqstp = (struct svc_rqst *) vrqstp;
struct svc_pool *pool = rqstp->rq_pool;
struct svc_xprt *perm_sock = list_entry(rqstp->rq_server->sv_permsocks.next, typeof(struct svc_xprt), xpt_list);
struct net *net = perm_sock->xpt_net;
struct nfsd_net *nn = net_generic(net, nfsd_net_id);
bool have_mutex = false;
/* At this point, the thread shares current->fs
* with the init process. We need to create files with the
@ -902,7 +904,44 @@ nfsd(void *vrqstp)
* The main request loop
*/
while (!svc_thread_should_stop(rqstp)) {
svc_recv(rqstp, 0);
switch (svc_recv(rqstp, 5 * HZ)) {
case -ETIMEDOUT:
/* No work arrived within the timeout window */
if (mutex_trylock(&nfsd_mutex)) {
if (pool->sp_nrthreads > pool->sp_nrthrmin) {
trace_nfsd_dynthread_kill(net, pool);
set_bit(RQ_VICTIM, &rqstp->rq_flags);
have_mutex = true;
} else {
mutex_unlock(&nfsd_mutex);
}
} else {
trace_nfsd_dynthread_trylock_fail(net, pool);
}
break;
case -EBUSY:
/* No idle threads; consider spawning another */
if (pool->sp_nrthreads < pool->sp_nrthrmax) {
if (mutex_trylock(&nfsd_mutex)) {
if (pool->sp_nrthreads < pool->sp_nrthrmax) {
int ret;
trace_nfsd_dynthread_start(net, pool);
ret = svc_new_thread(rqstp->rq_server, pool);
if (ret)
pr_notice_ratelimited("%s: unable to spawn new thread: %d\n",
__func__, ret);
}
mutex_unlock(&nfsd_mutex);
} else {
trace_nfsd_dynthread_trylock_fail(net, pool);
}
}
clear_bit(SP_TASK_STARTING, &pool->sp_flags);
break;
default:
break;
}
nfsd_file_net_dispose(nn);
}
@ -910,6 +949,8 @@ nfsd(void *vrqstp)
/* Release the thread */
svc_exit_thread(rqstp);
if (have_mutex)
mutex_unlock(&nfsd_mutex);
return 0;
}

35
fs/nfsd/trace.h
View file

@ -91,6 +91,41 @@ DEFINE_EVENT(nfsd_xdr_err_class, nfsd_##name##_err, \
DEFINE_NFSD_XDR_ERR_EVENT(garbage_args);
DEFINE_NFSD_XDR_ERR_EVENT(cant_encode);
DECLARE_EVENT_CLASS(nfsd_dynthread_class,
TP_PROTO(
const struct net *net,
const struct svc_pool *pool
),
TP_ARGS(net, pool),
TP_STRUCT__entry(
__field(unsigned int, netns_ino)
__field(unsigned int, pool_id)
__field(unsigned int, nrthreads)
__field(unsigned int, nrthrmin)
__field(unsigned int, nrthrmax)
),
TP_fast_assign(
__entry->netns_ino = net->ns.inum;
__entry->pool_id = pool->sp_id;
__entry->nrthreads = pool->sp_nrthreads;
__entry->nrthrmin = pool->sp_nrthrmin;
__entry->nrthrmax = pool->sp_nrthrmax;
),
TP_printk("pool=%u nrthreads=%u nrthrmin=%u nrthrmax=%u",
__entry->pool_id, __entry->nrthreads,
__entry->nrthrmin, __entry->nrthrmax
)
);
#define DEFINE_NFSD_DYNTHREAD_EVENT(name) \
DEFINE_EVENT(nfsd_dynthread_class, nfsd_dynthread_##name, \
TP_PROTO(const struct net *net, const struct svc_pool *pool), \
TP_ARGS(net, pool))
DEFINE_NFSD_DYNTHREAD_EVENT(start);
DEFINE_NFSD_DYNTHREAD_EVENT(kill);
DEFINE_NFSD_DYNTHREAD_EVENT(trylock_fail);
#define show_nfsd_may_flags(x) \
__print_flags(x, "|", \
{ NFSD_MAY_EXEC, "EXEC" }, \