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lockd: make NLM_HOST_MAX tunable

PATCH In review Olaf Kirch 2 participants 2 messages Aug 5, 2006 – Aug 15, 2006

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PATCH 1/22 lockd: make NLM_HOST_MAX tunable

From: Olaf Kirch <[email protected]>
Subject: lockd: make NLM_HOST_MAX tunable
Patch-mainline: not-yet

This patch makes NLM_HOST_MAX tunable, and exports the new variable as a sysctl.
The old value (64 clients) just wasn't adequate anymore.

Signed-off-by Olaf Kirch <[email protected]>
 fs/lockd/host.c             |    7 +++----
 fs/lockd/svc.c              |   10 ++++++++++
 include/linux/lockd/lockd.h |    1 +
 3 files changed, 14 insertions(+), 4 deletions(-)
fs/lockd/svc.c +10 -0
Index: build/fs/lockd/svc.c
===================================================================
@@ -59,6 +59,7 @@ static DECLARE_WAIT_QUEUE_HEAD(lockd_exi
 static unsigned long		nlm_grace_period;
 static unsigned long		nlm_timeout = LOCKD_DFLT_TIMEO;
 static int			nlm_udpport, nlm_tcpport;
+int				nlm_max_hosts = 256;
 
 /*
  * Constants needed for the sysctl interface.

@@ -367,6 +368,15 @@ static ctl_table nlm_sysctls[] = {
 		.extra1		= (int *) &nlm_port_min,
 		.extra2		= (int *) &nlm_port_max,
 	},
+	{
+		.ctl_name	= CTL_UNNUMBERED,
+		.procname	= "nlm_max_hosts",
+		.data		= &nlm_max_hosts,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec,
+	},
+
 	{ .ctl_name = 0 }
 };
include/linux/lockd/lockd.h +1 -0
Index: build/include/linux/lockd/lockd.h
===================================================================
@@ -144,6 +144,7 @@ extern struct svc_procedure	nlmsvc_proce
 #endif
 extern int			nlmsvc_grace_period;
 extern unsigned long		nlmsvc_timeout;
+extern int			nlm_max_hosts;
 
 /*
  * Lockd client functions
fs/lockd/host.c +3 -4
Index: build/fs/lockd/host.c
===================================================================
@@ -20,12 +20,11 @@
 
 
 #define NLMDBG_FACILITY		NLMDBG_HOSTCACHE
-#define NLM_HOST_MAX		64
 #define NLM_HOST_NRHASH		32
 #define NLM_ADDRHASH(addr)	(ntohl(addr) & (NLM_HOST_NRHASH-1))
 #define NLM_HOST_REBIND		(60 * HZ)
-#define NLM_HOST_EXPIRE		((nrhosts > NLM_HOST_MAX)? 300 * HZ : 120 * HZ)
-#define NLM_HOST_COLLECT	((nrhosts > NLM_HOST_MAX)? 120 * HZ :  60 * HZ)
+#define NLM_HOST_EXPIRE		((nrhosts > nlm_max_hosts)? 300 * HZ : 120 * HZ)
+#define NLM_HOST_COLLECT	((nrhosts > nlm_max_hosts)? 120 * HZ :  60 * HZ)
 #define NLM_HOST_ADDR(sv)	(&(sv)->s_nlmclnt->cl_xprt->addr)
 
 static struct nlm_host *	nlm_hosts[NLM_HOST_NRHASH];

@@ -128,7 +127,7 @@ nlm_lookup_host(int server, struct socka
 	INIT_LIST_HEAD(&host->h_granted);
 	INIT_LIST_HEAD(&host->h_reclaim);
 
-	if (++nrhosts > NLM_HOST_MAX)
+	if (++nrhosts > nlm_max_hosts)
 		next_gc = 0;
 
 nohost:

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#1 lore raw
Quoted 7 lines · On Saturday August 5, [email protected] wrote:

From: Olaf Kirch <[email protected]>
Subject: lockd: make NLM_HOST_MAX tunable
Patch-mainline: not-yet

This patch makes NLM_HOST_MAX tunable, and exports the new variable as a sysctl.
The old value (64 clients) just wasn't adequate anymore.

Why do we need NLM_HOST_MAX at all? And if we do, we need a better name, because it isn't really a maximum.

It is more of a threshold.
While there are fewer than this mean, we garbage collect every 2 minutes discarding hosts more than 5 minutes old.
When we exceed this threshold, we garbage collect every minutes (or every time a new host is allocated). and discard hosts older than 2 minutes.

It seems like we are picking an arbitrary point at which to switch from one arbitrary algorithm to another. Do we really want to do this?

I cannot see any good reason not to just pick one arbitrary algorithm and stick with that the whole time.
The only tunable might make sense is the max age before garbage collection removes hosts.

Am I missing something important?

NeilBrown

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