linux-kernel - RE: [PATCH 00/13] lib/generic-radix-tree: genradix bug fix and optimisations.

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Message-ID: <7894f0bc41764c0a8cb87f1482df7679@AcuMS.aculab.com>
Date:   Wed, 26 Aug 2020 09:56:56 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Marcelo Ricardo Leitner' <marcelo.leitner@...il.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "'linux-sctp@...r.kernel.org'" <linux-sctp@...r.kernel.org>,
        Eric Biggers <ebiggers@...nel.org>,
        'Catalin Marinas' <catalin.marinas@....com>,
        "'kent.overstreet@...il.com'" <kent.overstreet@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        'Neil Horman' <nhorman@...driver.com>
Subject: RE: [PATCH 00/13] lib/generic-radix-tree: genradix bug fix and
 optimisations.

From: 'Marcelo Ricardo Leitner'
> Sent: 25 August 2020 16:41
> 
> On Tue, Aug 25, 2020 at 02:52:34PM +0000, David Laight wrote:
> > The genradix code is used by SCTP for accessing per-stream data.
> > This means there are quite a lot of lookups but the code wasn't
> > really optimised at all.
> 
> My test box is down for the moment and will bring it on later today or
> tomorrow, so I can't test it yet. What should we expect as performance
> gains here?

I've just done quick test that shows ~1% improvement on an MTP3+M2PA
'double reflect' test using the 'test' userpart and a test program.
So there is quite a lot of extra protocol stack in the way.

The test is running ~200k very small data chunks/sec (tx and rx)
on a poor little 2.4GHz 8 core atom C2758.

However the 'baseline' kernel just locked up.
(Reports 5.8.0+ so must be late in the merge for rc1).

Annoyingly the Ubuntu 20.04 userspace won't show the kernel messages
(only a graphical login) - so I can see any kernel ooops messages.
I'm going to have to setup a serial console.
That'll need a trip into the office.

	David

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