netdev - RE: [PATCH net] x86: bpf_jit: fix compilation of large bpf programs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <063D6719AE5E284EB5DD2968C1650D6D1CB3ED4D@AcuExch.aculab.com>
Date:	Tue, 26 May 2015 15:47:19 +0000
From:	David Laight <David.Laight@...LAB.COM>
To:	'Eric Dumazet' <eric.dumazet@...il.com>
CC:	'Alexei Starovoitov' <ast@...mgrid.com>,
	"David S. Miller" <davem@...emloft.net>,
	Daniel Borkmann <daniel@...earbox.net>,
	Eric Dumazet <edumazet@...gle.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [PATCH net] x86: bpf_jit: fix compilation of large bpf programs

From: Eric Dumazet 
> Sent: 26 May 2015 16:30
> 
> > Yes, interesting, a benchmark that manages to run a lot of code 'cold cache'.
> 
> We have binaries here at Google with 400 or 500 MBytes of text.
> 
> Not benchmark, super real workloads you know.

Indeed, and a lot of the code is likely to be running 'cold cache'.

I was alluding to the problem where people will benchmark a small function
by running in 1000s of times in a tight loop with exactly the same data.
Not only is it 'hot cache' but any dynamic branch prediction is 'trained'
to the specific data.

	David