[PATCH] knfsd: allow admin to set nthreads per node

Add /proc/fs/nfsd/pool_threads which allows the sysadmin (or a userspace
daemon) to read and change the number of nfsd threads in each pool.  The
format is a list of space-separated integers, one per pool.

Signed-off-by: Greg Banks <gnb@melbourne.sgi.com>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 74 insertions, 0 deletions

diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index 0029cb290f18..19443056ec30 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -238,6 +238,80 @@ static int nfsd_init_socks(int port)
         return 0;
 }
 
+int nfsd_nrpools(void)
+{
+        if (nfsd_serv == NULL)
+                return 0;
+        else
+                return nfsd_serv->sv_nrpools;
+}
+
+int nfsd_get_nrthreads(int n, int *nthreads)
+{
+        int i = 0;
+
+        if (nfsd_serv != NULL) {
+                for (i = 0; i < nfsd_serv->sv_nrpools && i < n; i++)
+                        nthreads[i] = nfsd_serv->sv_pools[i].sp_nrthreads;
+        }
+
+        return 0;
+}
+
+int nfsd_set_nrthreads(int n, int *nthreads)
+{
+        int i = 0;
+        int tot = 0;
+        int err = 0;
+
+        if (nfsd_serv == NULL || n <= 0)
+                return 0;
+
+        if (n > nfsd_serv->sv_nrpools)
+                n = nfsd_serv->sv_nrpools;
+
+        /* enforce a global maximum number of threads */
+        tot = 0;
+        for (i = 0; i < n; i++) {
+                if (nthreads[i] > NFSD_MAXSERVS)
+                        nthreads[i] = NFSD_MAXSERVS;
+                tot += nthreads[i];
+        }
+        if (tot > NFSD_MAXSERVS) {
+                /* total too large: scale down requested numbers */
+                for (i = 0; i < n && tot > 0; i++) {
+                        int new = nthreads[i] * NFSD_MAXSERVS / tot;
+                        tot -= (nthreads[i] - new);
+                        nthreads[i] = new;
+                }
+                for (i = 0; i < n && tot > 0; i++) {
+                        nthreads[i]--;
+                        tot--;
+                }
+        }
+
+        /*
+         * There must always be a thread in pool 0; the admin
+         * can't shut down NFS completely using pool_threads.
+         */
+        if (nthreads[0] == 0)
+                nthreads[0] = 1;
+
+        /* apply the new numbers */
+        lock_kernel();
+        svc_get(nfsd_serv);
+        for (i = 0; i < n; i++) {
+                err = svc_set_num_threads(nfsd_serv, &nfsd_serv->sv_pools[i],
+                                          nthreads[i]);
+                if (err)
+                        break;
+        }
+        svc_destroy(nfsd_serv);
+        unlock_kernel();
+
+        return err;
+}
+
 int
 nfsd_svc(unsigned short port, int nrservs)
 {