From: "Alex Bennée" <alex.bennee@linaro.org>
To: Warner Losh <imp@bsdimp.com>
Cc: Richard Henderson <richard.henderson@linaro.org>,
QEMU Developers <qemu-devel@nongnu.org>,
laurent@vivier.eu
Subject: Re: [PATCH] linux-user: Reserve space for brk
Date: Mon, 20 Jan 2020 13:46:07 +0000 [thread overview]
Message-ID: <875zh62qcg.fsf@linaro.org> (raw)
In-Reply-To: <CANCZdfpNWaLOureeFTc78+EoAW+t9tu+NzcO7d61=AwuTQWDDQ@mail.gmail.com>
Warner Losh <imp@bsdimp.com> writes:
> On Fri, Jan 17, 2020 at 4:03 PM Richard Henderson <
> richard.henderson@linaro.org> wrote:
>
>> With bad luck, we can wind up with no space at all for brk,
>> which will generally cause the guest malloc to fail.
>>
> ...
>
>> The choice of 16MB is somewhat arbitrary. It's enough for libc
>> to get going, but without being so large that 32-bit guests or
>> 32-bit hosts are in danger of running out of virtual address space.
>> It is expected that libc will be able to fall back to mmap arenas
>> after the limited brk space is exhausted.
>>
>
> The biggest abuser of brk() is emacs, so according to one old wag
> this should be 80MB. Eighty Megabytes And Continuously Swapping.
Is this related to the dumper that it uses? I guess the new dumper
system isn't a problem as I was able to run emacs -nw -q on the buster
image without problem.
--
Alex Bennée
next prev parent reply other threads:[~2020-01-20 13:48 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-17 23:02 [PATCH] linux-user: Reserve space for brk Richard Henderson
2020-01-17 23:06 ` Warner Losh
2020-01-20 13:46 ` Alex Bennée [this message]
2020-01-20 11:25 ` Alex Bennée
2020-01-22 14:01 ` Laurent Vivier
2023-07-14 19:43 ` Michael Tokarev
2023-07-14 19:53 ` Michael Tokarev
2023-07-17 15:09 ` Michael Tokarev
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