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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=875zh62qcg.fsf@linaro.org \
--to=alex.bennee@linaro.org \
--cc=imp@bsdimp.com \
--cc=laurent@vivier.eu \
--cc=qemu-devel@nongnu.org \
--cc=richard.henderson@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).