linux-kernel - Re: [PATCH v4 00/17] khwasan: kernel hardware assisted address sanitizer

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Message-Id: <20180628124039.8a42ab5e2994fb2876ff4f75@linux-foundation.org>
Date:   Thu, 28 Jun 2018 12:40:39 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Andrey Konovalov <andreyknvl@...gle.com>
Cc:     Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Christoph Lameter <cl@...ux.com>,
        Mark Rutland <mark.rutland@....com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Marc Zyngier <marc.zyngier@....com>,
        Dave Martin <dave.martin@....com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        "Eric W . Biederman" <ebiederm@...ssion.com>,
        Ingo Molnar <mingo@...nel.org>,
        Paul Lawrence <paullawrence@...gle.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Arnd Bergmann <arnd@...db.de>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        kasan-dev <kasan-dev@...glegroups.com>,
        linux-doc@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        linux-sparse@...r.kernel.org,
        Linux Memory Management List <linux-mm@...ck.org>,
        Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Kostya Serebryany <kcc@...gle.com>,
        Evgeniy Stepanov <eugenis@...gle.com>,
        Lee Smith <Lee.Smith@....com>,
        Ramana Radhakrishnan <Ramana.Radhakrishnan@....com>,
        Jacob Bramley <Jacob.Bramley@....com>,
        Ruben Ayrapetyan <Ruben.Ayrapetyan@....com>,
        Jann Horn <jannh@...gle.com>,
        Mark Brand <markbrand@...gle.com>,
        Chintan Pandya <cpandya@...eaurora.org>
Subject: Re: [PATCH v4 00/17] khwasan: kernel hardware assisted address
 sanitizer

On Thu, 28 Jun 2018 20:29:07 +0200 Andrey Konovalov <andreyknvl@...gle.com> wrote:

> >> Slab memory usage after boot [2]:
> >> * ~40 kb for clean kernel
> >> * ~105 kb + 1/8th shadow ~= 118 kb for KASAN
> >> * ~47 kb + 1/16th shadow ~= 50 kb for KHWASAN
> >>
> >> Network performance [3]:
> >> * 8.33 Gbits/sec for clean kernel
> >> * 3.17 Gbits/sec for KASAN
> >> * 2.85 Gbits/sec for KHWASAN
> >>
> >> Note, that KHWASAN (compared to KASAN) doesn't require quarantine.
> >>
> >> [1] Time before the ext4 driver is initialized.
> >> [2] Measured as `cat /proc/meminfo | grep Slab`.
> >> [3] Measured as `iperf -s & iperf -c 127.0.0.1 -t 30`.
> >
> > The above doesn't actually demonstrate the whole point of the
> > patchset: to reduce KASAN's very high memory consumption?
> 
> You mean that memory usage numbers collected after boot don't give a
> representative picture of actual memory consumption on real workloads?
> 
> What kind of memory consumption testing would you like to see?

Well, 100kb or so is a teeny amount on virtually any machine.  I'm
assuming the savings are (much) more significant once the machine gets
loaded up and doing work?