| Message ID | 1405969902-11477-1-git-send-email-trond.myklebust@primarydata.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Jul 21, 2014 at 03:11:41PM -0400, Trond Myklebust wrote: > In some cases where the credentials are not often reused, we may want > to limit their total number just in order to make the negative lookups > in the hash table more manageable. Out of curiosity--how would somebody know that might need to set this? --b. > > Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> > --- > net/sunrpc/auth.c | 44 +++++++++++++++++++++++++++++++++++--------- > 1 file changed, 35 insertions(+), 9 deletions(-) > > diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c > index 2bc7bb82b162..360decdddc78 100644 > --- a/net/sunrpc/auth.c > +++ b/net/sunrpc/auth.c > @@ -80,6 +80,10 @@ static struct kernel_param_ops param_ops_hashtbl_sz = { > module_param_named(auth_hashtable_size, auth_hashbits, hashtbl_sz, 0644); > MODULE_PARM_DESC(auth_hashtable_size, "RPC credential cache hashtable size"); > > +static unsigned long auth_max_cred_cachesize = ULONG_MAX; > +module_param(auth_max_cred_cachesize, ulong, 0644); > +MODULE_PARM_DESC(auth_max_cred_cachesize, "RPC credential maximum total cache size"); > + > static u32 > pseudoflavor_to_flavor(u32 flavor) { > if (flavor > RPC_AUTH_MAXFLAVOR) > @@ -481,6 +485,20 @@ rpcauth_prune_expired(struct list_head *free, int nr_to_scan) > return freed; > } > > +static unsigned long > +rpcauth_cache_do_shrink(int nr_to_scan) > +{ > + LIST_HEAD(free); > + unsigned long freed; > + > + spin_lock(&rpc_credcache_lock); > + freed = rpcauth_prune_expired(&free, nr_to_scan); > + spin_unlock(&rpc_credcache_lock); > + rpcauth_destroy_credlist(&free); > + > + return freed; > +} > + > /* > * Run memory cache shrinker. > */ > @@ -488,9 +506,6 @@ static unsigned long > rpcauth_cache_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) > > { > - LIST_HEAD(free); > - unsigned long freed; > - > if ((sc->gfp_mask & GFP_KERNEL) != GFP_KERNEL) > return SHRINK_STOP; > > @@ -498,12 +513,7 @@ rpcauth_cache_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) > if (list_empty(&cred_unused)) > return SHRINK_STOP; > > - spin_lock(&rpc_credcache_lock); > - freed = rpcauth_prune_expired(&free, sc->nr_to_scan); > - spin_unlock(&rpc_credcache_lock); > - rpcauth_destroy_credlist(&free); > - > - return freed; > + return rpcauth_cache_do_shrink(sc->nr_to_scan); > } > > static unsigned long > @@ -513,6 +523,21 @@ rpcauth_cache_shrink_count(struct shrinker *shrink, struct shrink_control *sc) > return (number_cred_unused / 100) * sysctl_vfs_cache_pressure; > } > > +static void > +rpcauth_cache_enforce_limit(void) > +{ > + unsigned long diff; > + unsigned int nr_to_scan; > + > + if (number_cred_unused <= auth_max_cred_cachesize) > + return; > + diff = number_cred_unused - auth_max_cred_cachesize; > + nr_to_scan = 100; > + if (diff < nr_to_scan) > + nr_to_scan = diff; > + rpcauth_cache_do_shrink(nr_to_scan); > +} > + > /* > * Look up a process' credentials in the authentication cache > */ > @@ -566,6 +591,7 @@ rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred, > } else > list_add_tail(&new->cr_lru, &free); > spin_unlock(&cache->lock); > + rpcauth_cache_enforce_limit(); > found: > if (test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags) && > cred->cr_ops->cr_init != NULL && > -- > 1.9.3 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Jul 21, 2014 at 5:09 PM, J. Bruce Fields <bfields@fieldses.org> wrote: > On Mon, Jul 21, 2014 at 03:11:41PM -0400, Trond Myklebust wrote: >> In some cases where the credentials are not often reused, we may want >> to limit their total number just in order to make the negative lookups >> in the hash table more manageable. > > Out of curiosity--how would somebody know that might need to set this? It would have to be for very unusual workloads (which is why we haven't done it before). Something like a web-server that creates uids/gids on the fly, uses them for a few transactions and then doesn't need to use them again for a long while. You would need to use something like 'perf' or a similar profiler to show you are spending a lot of time in the rpc_auth lookup code. Note that we do have the ability already to change the hash table size to mitigate the above problem, but if the workload really is using throw-away uid/gids, then this is going to work better. Cheers Trond > --b. > >> >> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> >> --- >> net/sunrpc/auth.c | 44 +++++++++++++++++++++++++++++++++++--------- >> 1 file changed, 35 insertions(+), 9 deletions(-) >> >> diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c >> index 2bc7bb82b162..360decdddc78 100644 >> --- a/net/sunrpc/auth.c >> +++ b/net/sunrpc/auth.c >> @@ -80,6 +80,10 @@ static struct kernel_param_ops param_ops_hashtbl_sz = { >> module_param_named(auth_hashtable_size, auth_hashbits, hashtbl_sz, 0644); >> MODULE_PARM_DESC(auth_hashtable_size, "RPC credential cache hashtable size"); >> >> +static unsigned long auth_max_cred_cachesize = ULONG_MAX; >> +module_param(auth_max_cred_cachesize, ulong, 0644); >> +MODULE_PARM_DESC(auth_max_cred_cachesize, "RPC credential maximum total cache size"); >> + >> static u32 >> pseudoflavor_to_flavor(u32 flavor) { >> if (flavor > RPC_AUTH_MAXFLAVOR) >> @@ -481,6 +485,20 @@ rpcauth_prune_expired(struct list_head *free, int nr_to_scan) >> return freed; >> } >> >> +static unsigned long >> +rpcauth_cache_do_shrink(int nr_to_scan) >> +{ >> + LIST_HEAD(free); >> + unsigned long freed; >> + >> + spin_lock(&rpc_credcache_lock); >> + freed = rpcauth_prune_expired(&free, nr_to_scan); >> + spin_unlock(&rpc_credcache_lock); >> + rpcauth_destroy_credlist(&free); >> + >> + return freed; >> +} >> + >> /* >> * Run memory cache shrinker. >> */ >> @@ -488,9 +506,6 @@ static unsigned long >> rpcauth_cache_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) >> >> { >> - LIST_HEAD(free); >> - unsigned long freed; >> - >> if ((sc->gfp_mask & GFP_KERNEL) != GFP_KERNEL) >> return SHRINK_STOP; >> >> @@ -498,12 +513,7 @@ rpcauth_cache_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) >> if (list_empty(&cred_unused)) >> return SHRINK_STOP; >> >> - spin_lock(&rpc_credcache_lock); >> - freed = rpcauth_prune_expired(&free, sc->nr_to_scan); >> - spin_unlock(&rpc_credcache_lock); >> - rpcauth_destroy_credlist(&free); >> - >> - return freed; >> + return rpcauth_cache_do_shrink(sc->nr_to_scan); >> } >> >> static unsigned long >> @@ -513,6 +523,21 @@ rpcauth_cache_shrink_count(struct shrinker *shrink, struct shrink_control *sc) >> return (number_cred_unused / 100) * sysctl_vfs_cache_pressure; >> } >> >> +static void >> +rpcauth_cache_enforce_limit(void) >> +{ >> + unsigned long diff; >> + unsigned int nr_to_scan; >> + >> + if (number_cred_unused <= auth_max_cred_cachesize) >> + return; >> + diff = number_cred_unused - auth_max_cred_cachesize; >> + nr_to_scan = 100; >> + if (diff < nr_to_scan) >> + nr_to_scan = diff; >> + rpcauth_cache_do_shrink(nr_to_scan); >> +} >> + >> /* >> * Look up a process' credentials in the authentication cache >> */ >> @@ -566,6 +591,7 @@ rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred, >> } else >> list_add_tail(&new->cr_lru, &free); >> spin_unlock(&cache->lock); >> + rpcauth_cache_enforce_limit(); >> found: >> if (test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags) && >> cred->cr_ops->cr_init != NULL && >> -- >> 1.9.3 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c index 2bc7bb82b162..360decdddc78 100644 --- a/net/sunrpc/auth.c +++ b/net/sunrpc/auth.c @@ -80,6 +80,10 @@ static struct kernel_param_ops param_ops_hashtbl_sz = { module_param_named(auth_hashtable_size, auth_hashbits, hashtbl_sz, 0644); MODULE_PARM_DESC(auth_hashtable_size, "RPC credential cache hashtable size"); +static unsigned long auth_max_cred_cachesize = ULONG_MAX; +module_param(auth_max_cred_cachesize, ulong, 0644); +MODULE_PARM_DESC(auth_max_cred_cachesize, "RPC credential maximum total cache size"); + static u32 pseudoflavor_to_flavor(u32 flavor) { if (flavor > RPC_AUTH_MAXFLAVOR) @@ -481,6 +485,20 @@ rpcauth_prune_expired(struct list_head *free, int nr_to_scan) return freed; } +static unsigned long +rpcauth_cache_do_shrink(int nr_to_scan) +{ + LIST_HEAD(free); + unsigned long freed; + + spin_lock(&rpc_credcache_lock); + freed = rpcauth_prune_expired(&free, nr_to_scan); + spin_unlock(&rpc_credcache_lock); + rpcauth_destroy_credlist(&free); + + return freed; +} + /* * Run memory cache shrinker. */ @@ -488,9 +506,6 @@ static unsigned long rpcauth_cache_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) { - LIST_HEAD(free); - unsigned long freed; - if ((sc->gfp_mask & GFP_KERNEL) != GFP_KERNEL) return SHRINK_STOP; @@ -498,12 +513,7 @@ rpcauth_cache_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) if (list_empty(&cred_unused)) return SHRINK_STOP; - spin_lock(&rpc_credcache_lock); - freed = rpcauth_prune_expired(&free, sc->nr_to_scan); - spin_unlock(&rpc_credcache_lock); - rpcauth_destroy_credlist(&free); - - return freed; + return rpcauth_cache_do_shrink(sc->nr_to_scan); } static unsigned long @@ -513,6 +523,21 @@ rpcauth_cache_shrink_count(struct shrinker *shrink, struct shrink_control *sc) return (number_cred_unused / 100) * sysctl_vfs_cache_pressure; } +static void +rpcauth_cache_enforce_limit(void) +{ + unsigned long diff; + unsigned int nr_to_scan; + + if (number_cred_unused <= auth_max_cred_cachesize) + return; + diff = number_cred_unused - auth_max_cred_cachesize; + nr_to_scan = 100; + if (diff < nr_to_scan) + nr_to_scan = diff; + rpcauth_cache_do_shrink(nr_to_scan); +} + /* * Look up a process' credentials in the authentication cache */ @@ -566,6 +591,7 @@ rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred, } else list_add_tail(&new->cr_lru, &free); spin_unlock(&cache->lock); + rpcauth_cache_enforce_limit(); found: if (test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags) && cred->cr_ops->cr_init != NULL &&
In some cases where the credentials are not often reused, we may want to limit their total number just in order to make the negative lookups in the hash table more manageable. Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> --- net/sunrpc/auth.c | 44 +++++++++++++++++++++++++++++++++++--------- 1 file changed, 35 insertions(+), 9 deletions(-)