linux-kernel - Re: [PATCH v36 00/13] /dev/random

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Message-ID: <34318060.ATrlOLLGV9@tauon.chronox.de>
Date:   Tue, 10 Nov 2020 11:22:14 +0100
From:   Stephan Mueller <smueller@...onox.de>
To:     Torsten Duwe <duwe@....de>
Cc:     Willy Tarreau <w@....eu>, "Theodore Y. Ts'o" <tytso@....edu>,
        linux-crypto@...r.kernel.org, Nicolai Stange <nstange@...e.de>,
        LKML <linux-kernel@...r.kernel.org>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        "Alexander E. Patrakov" <patrakov@...il.com>,
        "Ahmed S. Darwish" <darwish.07@...il.com>,
        Matthew Garrett <mjg59@...f.ucam.org>,
        Vito Caputo <vcaputo@...garu.com>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Jan Kara <jack@...e.cz>, Ray Strode <rstrode@...hat.com>,
        William Jon McCann <mccann@....edu>,
        zhangjs <zachary@...shancloud.com>,
        Andy Lutomirski <luto@...nel.org>,
        Florian Weimer <fweimer@...hat.com>,
        Lennart Poettering <mzxreary@...inter.de>,
        Peter Matthias <matthias.peter@....bund.de>,
        Marcelo Henrique Cerri <marcelo.cerri@...onical.com>,
        Neil Horman <nhorman@...hat.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Julia Lawall <julia.lawall@...ia.fr>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Andy Lavr <andy.lavr@...il.com>,
        Eric Biggers <ebiggers@...nel.org>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        Petr Tesarik <ptesarik@...e.cz>
Subject: Re: [PATCH v36 00/13] /dev/random - a new approach

Am Montag, 19. Oktober 2020, 21:28:50 CET schrieb Stephan Müller:

Hi,
> 
> * Performance
> 
>  - Faster by up to 75% in the critical code path of the interrupt handler
>    depending on data collection size configurable at kernel compile time -
>    the default is about equal in performance with existing /dev/random as
>    outlined in [2] section 4.2.

By streamlining the implementation a bit, the LRNG interrupt handler now 
operates about 130% faster than the existing /dev/random (average of 97 cycles 
of the existing /dev/random code vs. an average of 42 cycles of the LRNG). 
This fast operation is the default now due to patch [2]. The conceptual data 
handling outlined in [3] section 2.2 remains unchanged.

Even the addition of health tests applied to the noise source data would still 
result in a faster interrupt handling code (average of 97 cycles of the 
existing /dev/random code vs on average 78 cycles of the LRNG).

[1] https://github.com/smuellerDD/lrng/commit/
10b74b242950371273e38df78060e258d9d3ea40

[2] https://github.com/smuellerDD/lrng/commit/
383b087653c21cf20984f5508befa57e96f685ba

[3] https://chronox.de/lrng/doc/lrng.pdf

Ciao
Stephan