linux-kernel - Re: [PATCH] nfsd: report the requested maximum number of threads instead of number running

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Message-ID: <6944906a-9256-4f10-88fa-822a639eb5eb@gmail.com>
Date: Thu, 5 Feb 2026 10:01:21 +0000
From: Mike Owen <mjnowen@...il.com>
To: Jeff Layton <jlayton@...nel.org>, Chuck Lever <cel@...nel.org>,
 Chuck Lever <chuck.lever@...cle.com>, NeilBrown <neil@...wn.name>,
 Olga Kornievskaia <okorniev@...hat.com>, Dai Ngo <Dai.Ngo@...cle.com>,
 Tom Talpey <tom@...pey.com>
Cc: linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] nfsd: report the requested maximum number of threads
 instead of number running

Hi,
I currently rely on: "/proc/net/rpc/nfsd" to retrieve the current number of threads via "th": https://svennd.be/nfsd-stats-explained-procnetrpcnfsd/
After the various patches to introduce dynamic threading, where in the future, would a user retrieve the currently set min, max and actual running thread count reliably?
Would be lovely if the man page indicated this.
Thanks,
Mike

On 04/02/2026 19:13, Jeff Layton wrote:
> On Wed, 2026-02-04 at 13:51 -0500, Chuck Lever wrote:
>>
>> On Wed, Feb 4, 2026, at 12:23 PM, Jeff Layton wrote:
>>> The current netlink and /proc interfaces deviate from their traditional
>>> values when dynamic threading is enabled, and there is currently no way
>>> to know what the current setting is. This patch brings the reporting
>>> back in line with traditional behavior.
>>>
>>> Make these interfaces report the requested maximum number of threads
>>> instead of the number currently running.
>>>
>>> Fixes: d8316b837c2c ("nfsd: add controls to set the minimum number of 
>>> threads per pool")
>>> Signed-off-by: Jeff Layton <jlayton@...nel.org>
>>> ---
>>> I think this is less surprising than the current behavior of what's in
>>> Chuck's tree. We could also consider adding netlink attributes to report
>>> the number of running threads, but you can get that info from ps too.
>>> ---
>>>  fs/nfsd/nfsctl.c | 2 +-
>>>  fs/nfsd/nfssvc.c | 7 ++++---
>>>  2 files changed, 5 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
>>> index 
>>> 4d8e3c1a7be3b3a4e4f5248b27b60d6b3ae88d51..178c7646b2e25630b85de937d7ced18947c047f9 
>>> 100644
>>> --- a/fs/nfsd/nfsctl.c
>>> +++ b/fs/nfsd/nfsctl.c
>>> @@ -1700,7 +1700,7 @@ int nfsd_nl_threads_get_doit(struct sk_buff *skb, 
>>> struct genl_info *info)
>>>  			struct svc_pool *sp = &nn->nfsd_serv->sv_pools[i];
>>>
>>>  			err = nla_put_u32(skb, NFSD_A_SERVER_THREADS,
>>> -					  sp->sp_nrthreads);
>>> +					  sp->sp_nrthrmax);
>>>  			if (err)
>>>  				goto err_unlock;
>>>  		}
>>> diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
>>> index 
>>> 8184514c58de8e396795cd4714a04d66d9637f17..be0add971c2d994948c3e8fca19bcf6f3c75dfaf 
>>> 100644
>>> --- a/fs/nfsd/nfssvc.c
>>> +++ b/fs/nfsd/nfssvc.c
>>> @@ -239,12 +239,13 @@ static void nfsd_net_free(struct percpu_ref *ref)
>>>
>>>  int nfsd_nrthreads(struct net *net)
>>>  {
>>> -	int rv = 0;
>>> +	int i, rv = 0;
>>>  	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
>>>
>>>  	mutex_lock(&nfsd_mutex);
>>>  	if (nn->nfsd_serv)
>>> -		rv = nn->nfsd_serv->sv_nrthreads;
>>> +		for (i = 0; i < nn->nfsd_serv->sv_nrpools; ++i)
>>> +			rv += nn->nfsd_serv->sv_pools[i].sp_nrthrmax;
>>>  	mutex_unlock(&nfsd_mutex);
>>>  	return rv;
>>>  }
>>> @@ -673,7 +674,7 @@ int nfsd_get_nrthreads(int n, int *nthreads, struct 
>>> net *net)
>>>
>>>  	if (serv)
>>>  		for (i = 0; i < serv->sv_nrpools && i < n; i++)
>>> -			nthreads[i] = serv->sv_pools[i].sp_nrthreads;
>>> +			nthreads[i] = serv->sv_pools[i].sp_nrthrmax;
>>>  	return 0;
>>>  }
>>
>> AI code review observes that:
>>
>> The documentation should be updated to reflect that these interfaces
>> now report the configured maximum threads rather than running threads:
>>
>> 1. Documentation/netlink/specs/nfsd.yaml line 168 - threads-get is
>>    documented as "get the number of running threads" but now returns
>>    the configured maximum
>> 2. fs/nfsd/nfsctl.c lines 387-405 - The write_threads() docstring
>>    says it reports "the number of running NFSD threads" but now
>>    reports the configured maximum
>> 3. fs/nfsd/nfsctl.c lines 1666-1673 - The nfsd_nl_threads_get_doit()
>>    docstring says "get the number of running threads"
>>
> 
> Ok, I'll do that for v2.
> 
> Thanks,