Re: [PATCH 05/15] RDS: increase size of hash-table to 8K

From	santosh shilimkar <santosh.shilimkar@oracle.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 05/15] RDS: increase size of hash-table to 8K
Date	2015-09-21 18:00 +0200
Message-ID	<qbbFw-2I0-23@gated-at.bofh.it> (permalink)
References	<qazqy-7hf-9@gated-at.bofh.it> <qazqz-7hf-29@gated-at.bofh.it> <qb4NJ-1lP-19@gated-at.bofh.it>
Organization	Oracle Corporation

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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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Thread

[PATCH 00/15] RDS: connection scalability and performance improvements Santosh Shilimkar <santosh.shilimkar@oracle.com> - 2015-09-20 01:10 +0200
  [PATCH 13/15] RDS: mark rds_ib_fmr_wq static Santosh Shilimkar <santosh.shilimkar@oracle.com> - 2015-09-20 01:10 +0200
  [PATCH 06/15] RDS: defer the over_batch work to send worker Santosh Shilimkar <santosh.shilimkar@oracle.com> - 2015-09-20 01:10 +0200
  [PATCH 04/15] RDS: Use per-bucket rw lock for bind hash-table Santosh Shilimkar <santosh.shilimkar@oracle.com> - 2015-09-20 01:10 +0200
  [PATCH 08/15] RDS: ack more receive completions to improve performance Santosh Shilimkar <santosh.shilimkar@oracle.com> - 2015-09-20 01:10 +0200
  [PATCH 15/15] RDS: split mr pool to improve 8K messages performance Santosh Shilimkar <santosh.shilimkar@oracle.com> - 2015-09-20 01:10 +0200
  [PATCH 14/15] RDS: use max_mr from HCA caps than max_fmr Santosh Shilimkar <santosh.shilimkar@oracle.com> - 2015-09-20 01:10 +0200
  [PATCH 12/15] RDS: use already available pool handle from ibmr Santosh Shilimkar <santosh.shilimkar@oracle.com> - 2015-09-20 01:10 +0200
  [PATCH 03/15] RDS: fix rds_sock reference bug while doing bind Santosh Shilimkar <santosh.shilimkar@oracle.com> - 2015-09-20 01:10 +0200
  [PATCH 07/15] RDS: use rds_send_xmit() state instead of RDS_LL_SEND_FULL Santosh Shilimkar <santosh.shilimkar@oracle.com> - 2015-09-20 01:10 +0200
  [PATCH 05/15] RDS: increase size of hash-table to 8K Santosh Shilimkar <santosh.shilimkar@oracle.com> - 2015-09-20 01:10 +0200
    RE: [PATCH 05/15] RDS: increase size of hash-table to 8K David Laight <David.Laight@ACULAB.COM> - 2015-09-21 10:40 +0200
      Re: [PATCH 05/15] RDS: increase size of hash-table to 8K santosh shilimkar <santosh.shilimkar@oracle.com> - 2015-09-21 18:00 +0200
    Re: [PATCH 05/15] RDS: increase size of hash-table to 8K David Miller <davem@davemloft.net> - 2015-09-22 01:10 +0200
      Re: [PATCH 05/15] RDS: increase size of hash-table to 8K santosh shilimkar <santosh.shilimkar@oracle.com> - 2015-09-22 02:00 +0200
        Re: [PATCH 05/15] RDS: increase size of hash-table to 8K santosh shilimkar <santosh.shilimkar@oracle.com> - 2015-09-23 20:10 +0200
  [PATCH 02/15] RDS: make socket bind/release locking scheme simple and more efficient Santosh Shilimkar <santosh.shilimkar@oracle.com> - 2015-09-20 01:10 +0200
  [PATCH 10/15] RDS: handle rds_ibdev release case instead of crashing the kernel Santosh Shilimkar <santosh.shilimkar@oracle.com> - 2015-09-20 01:20 +0200
  [PATCH 01/15] RDS: use kfree_rcu in rds_ib_remove_ipaddr Santosh Shilimkar <santosh.shilimkar@oracle.com> - 2015-09-20 01:20 +0200
  [PATCH 11/15] RDS: fix the rds_ib_fmr_wq kick call Santosh Shilimkar <santosh.shilimkar@oracle.com> - 2015-09-20 01:20 +0200
  Re: [PATCH 00/15] RDS: connection scalability and performance  improvements Sagi Grimberg <sagig@dev.mellanox.co.il> - 2015-09-20 10:40 +0200
    Re: [PATCH 00/15] RDS: connection scalability and performance  improvements santosh shilimkar <santosh.shilimkar@oracle.com> - 2015-09-21 18:10 +0200

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