From mboxrd@z Thu Jan 1 00:00:00 1970 From: santosh shilimkar Subject: Re: [PATCH 05/15] RDS: increase size of hash-table to 8K Date: Wed, 23 Sep 2015 11:06:16 -0700 Message-ID: <5602EA18.7080404@oracle.com> References: <1442703892-26692-1-git-send-email-santosh.shilimkar@oracle.com> <1442703892-26692-6-git-send-email-santosh.shilimkar@oracle.com> <20150921.160527.1218605543469993281.davem@davemloft.net> <560098ED.7@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, ssantosh@kernel.org To: David Miller Return-path: In-Reply-To: <560098ED.7@oracle.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Hi Dave, On 9/21/2015 4:55 PM, santosh shilimkar wrote: > On 9/21/2015 4:05 PM, David Miller wrote: >> From: Santosh Shilimkar >> 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 >>> Signed-off-by: Santosh Shilimkar >> >> 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. > > OK. Thanks for AF_NETLINK pointer. I will look it up. > I will follow your advice on resizable hash table usage. It seems to be neat and fits well. But I want to make sure that the implementation works for all the workloads so it will take some time. Hopefully I can get that ready with testing for 4.5. So for now,lets just drop the $subject patch from this series. Do you want me to resend the series with the $subject patch dropped, or you can apply rest of the series except this one. Let me know. Thanks !! Regards, Santosh