Messages in this thread | | | Subject | Re: [PATCH 05/15] RDS: increase size of hash-table to 8K | From | santosh shilimkar <> | Date | Mon, 21 Sep 2015 08:52:07 -0700 |
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On 9/21/2015 1:31 AM, David Laight wrote: > From: Santosh Shilimkar >> Sent: 20 September 2015 00:05 >> Even with per bucket locking scheme, in a massive parallel >> system with active rds sockets which could be in excess of multiple >> of 10K, rds_bin_lookup() workload is significant because of smaller >> hashtable size. >> >> With some tests, it was found that we get modest but still nice >> reduction in rds_bind_lookup with bigger bucket. >> >> Hashtable Baseline(1k) Delta >> 2048: 8.28% -2.45% >> 4096: 8.28% -4.60% >> 8192: 8.28% -6.46% >> 16384: 8.28% -6.75% >> >> Based on the data, we set 8K as the bind hash-table size. > > Can't you use of on the dynamically sizing hash tables? > 8k hash table entries is OTT for a lot of systems. > Do you know an example in Linux kernel uses that ? What I certainly don't want is over-head of re-sizing whenever that happens in running systems running multiple databases.
Memory is certainly not an issue on the systems where RDS has been deployed. I certainly don't want to over-use the memory but in the system where RDS being used and also amount of connection it needs to handle, it needs bigger bucket.
Regards, Santosh
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