From: "NeilBrown" <neilb@suse.de>
To: "Chuck Lever III" <chuck.lever@oracle.com>
Cc: "Bruce Fields" <bfields@fieldses.org>,
"Linux NFS Mailing List" <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH 05/19] SUNRPC: use sv_lock to protect updates to sv_nrthreads.
Date: Mon, 29 Nov 2021 11:11:17 +1100 [thread overview]
Message-ID: <163814467728.26075.9969415181039584323@noble.neil.brown.name> (raw)
In-Reply-To: <3877F926-545B-41AF-8C0C-80582E83F1FE@oracle.com>
On Wed, 24 Nov 2021, Chuck Lever III wrote:
> > @@ -639,7 +639,10 @@ svc_prepare_thread(struct svc_serv *serv, struct svc_pool *pool, int node)
> > return ERR_PTR(-ENOMEM);
> >
> > svc_get(serv);
> > - serv->sv_nrthreads++;
> > + spin_lock_bh(&serv->sv_lock);
> > + serv->sv_nrthreads += 1;
> > + spin_unlock_bh(&serv->sv_lock);
>
> atomic_t would be somewhat lighter weight. Can it be used here
> instead?
>
We could.... but sv_nrthreads is read-mostly. There are 11 places
where we would need to call "atomic_read()", and just two where we
benefit from the simplicity of atomic_inc/dec.
And even if I did achieve dynamic threads count management, we would not
be changing sv_nrthreads often enough that any performance difference
would be noticeable.
So I'd rather stick with using the spinlock and keeping the read-side
simple.
Thanks,
NeilBrown
next prev parent reply other threads:[~2021-11-29 0:13 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-23 1:29 [PATCH 00/19 v2] SUNRPC: clean up server thread management NeilBrown
2021-11-23 1:29 ` [PATCH 15/19] lockd: rename lockd_create_svc() to lockd_get() NeilBrown
2021-11-23 1:29 ` [PATCH 13/19] lockd: move svc_exit_thread() into the thread NeilBrown
2021-11-23 1:29 ` [PATCH 06/19] NFSD: narrow nfsd_mutex protection in nfsd thread NeilBrown
2021-11-23 1:29 ` [PATCH 05/19] SUNRPC: use sv_lock to protect updates to sv_nrthreads NeilBrown
2021-11-23 16:43 ` Chuck Lever III
2021-11-29 0:11 ` NeilBrown [this message]
2021-11-23 1:29 ` [PATCH 10/19] lockd: introduce nlmsvc_serv NeilBrown
2021-11-23 1:29 ` [PATCH 14/19] lockd: introduce lockd_put() NeilBrown
2021-11-23 1:29 ` [PATCH 02/19] NFSD: handle error better in write_ports_addfd() NeilBrown
2021-11-23 16:44 ` Chuck Lever III
2021-11-28 23:49 ` NeilBrown
2021-11-23 1:29 ` [PATCH 12/19] lockd: move lockd_start_svc() call into lockd_create_svc() NeilBrown
2021-11-23 1:29 ` [PATCH 16/19] SUNRPC: move the pool_map definitions (back) into svc.c NeilBrown
2021-11-23 1:29 ` [PATCH 07/19] NFSD: Make it possible to use svc_set_num_threads_sync NeilBrown
2021-11-23 1:29 ` [PATCH 04/19] nfsd: make nfsd_stats.th_cnt atomic_t NeilBrown
2021-11-23 1:29 ` [PATCH 01/19] SUNRPC/NFSD: clean up get/put functions NeilBrown
2021-11-23 16:45 ` Chuck Lever III
2021-11-28 23:36 ` NeilBrown
2021-11-23 1:29 ` [PATCH 18/19] lockd: use svc_set_num_threads() for thread start and stop NeilBrown
2021-11-23 1:29 ` [PATCH 09/19] NFSD: simplify locking for network notifier NeilBrown
2021-11-23 1:29 ` [PATCH 11/19] lockd: simplify management of network status notifiers NeilBrown
2021-11-23 1:29 ` [PATCH 08/19] SUNRPC: discard svo_setup and rename svc_set_num_threads_sync() NeilBrown
2021-11-23 1:29 ` [PATCH 19/19] NFS: switch the callback service back to non-pooled NeilBrown
2021-11-23 1:29 ` [PATCH 03/19] SUNRPC: stop using ->sv_nrthreads as a refcount NeilBrown
2021-11-23 1:29 ` [PATCH 17/19] SUNRPC: always treat sv_nrpools==1 as "not pooled" NeilBrown
2021-11-23 14:49 ` [PATCH 00/19 v2] SUNRPC: clean up server thread management J. Bruce Fields
2021-11-24 18:42 ` Chuck Lever III
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