diff options
| author | Anton Blanchard <anton@samba.org> | 2009-04-27 16:42:24 +0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2009-04-27 16:42:24 +0400 |
| commit | c9503e0fe052020e0294cd07d0ecd982eb7c9177 (patch) | |
| tree | aa0425fc1f30ebdf8d7455cf59db5c3ea2c7dfd0 | |
| parent | 2296e5a0136f7ba64c99f3a48a55a687aa9abcc8 (diff) | |
| download | linux-c9503e0fe052020e0294cd07d0ecd982eb7c9177.tar.xz | |
ipv4: Limit size of route cache hash table
Right now we have no upper limit on the size of the route cache hash table.
On a 128GB POWER6 box it ends up as 32MB:
IP route cache hash table entries: 4194304 (order: 9, 33554432 bytes)
It would be nice to cap this for memory consumption reasons, but a massive
hashtable also causes a significant spike when measuring OS jitter.
With a 32MB hashtable and 4 million entries, rt_worker_func is taking
5 ms to complete. On another system with more memory it's taking 14 ms.
Even though rt_worker_func does call cond_sched() to limit its impact,
in an HPC environment we want to keep all sources of OS jitter to a minimum.
With the patch applied we limit the number of entries to 512k which
can still be overriden by using the rt_entries boot option:
IP route cache hash table entries: 524288 (order: 6, 4194304 bytes)
With this patch rt_worker_func now takes 0.460 ms on the same system.
Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/ipv4/route.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/ipv4/route.c b/net/ipv4/route.c index c40debe51b38..c4c60e9f068a 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -3397,7 +3397,7 @@ int __init ip_rt_init(void) 0, &rt_hash_log, &rt_hash_mask, - 0); + rhash_entries ? 0 : 512 * 1024); memset(rt_hash_table, 0, (rt_hash_mask + 1) * sizeof(struct rt_hash_bucket)); rt_hash_lock_init(); |