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

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From: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Date: Sat, 19 Sep 2015 19:04:42 -0400

> 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 siginificant 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.
> 
> Signed-off-by: Santosh Shilimkar <ssantosh@kernel.org>
> Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>

Like others I would strongly prefer that you use a dynamically sized
hash table.

Eating 8k just because a module just happened to get loaded is really
not appropriate.

And there are many other places that use such a scheme, one example is
the AF_NETLINK socket hash table.
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[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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