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Re: [RFC] nptl: change default stack guard size of threads

From: Florian Weimer <fweimer at redhat dot com>
To: Carlos O'Donell <carlos at redhat dot com>, Wilco Dijkstra <Wilco dot Dijkstra at arm dot com>, Szabolcs Nagy <Szabolcs dot Nagy at arm dot com>, GNU C Library <libc-alpha at sourceware dot org>
Cc: nd <nd at arm dot com>, Jeff Law <law at redhat dot com>, Richard Earnshaw <Richard dot Earnshaw at arm dot com>, Rich Felker <dalias at libc dot org>, James Greenhalgh <James dot Greenhalgh at arm dot com>
Date: Wed, 6 Dec 2017 13:53:38 +0100
Subject: Re: [RFC] nptl: change default stack guard size of threads
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References: <5A1ECB40.9080801@arm.com> <76c38ecf-6497-c96c-5c8c-95cceed100a5@redhat.com> <5A1EFF28.9050406@arm.com> <5c796246-1907-8cf4-00fc-eee11614b092@redhat.com> <HE1PR0801MB205834BDB77C2208C953FD2E833B0@HE1PR0801MB2058.eurprd08.prod.outlook.com> <fd118128-6a08-b1a2-a38f-680b46756691@redhat.com>

On 11/29/2017 11:38 PM, Carlos O'Donell wrote:

On 11/29/2017 02:28 PM, Wilco Dijkstra wrote:

Why should it be any different from LP64? Typical page size will still be
64KB, so a 4KB guard would be rounded up to 64KB. An ILP32 system
with 64KB pages could create  ~30000 threads per process. Does that
make it unusable?


... and this is already configurable via pthread_attr_setguardsize(), so
you *could* tune a system to have smaller guards against the recommendation
of the runtime authors?


Sure, if you recompile your application.  That's not really a solution IMHO.

Florian

Follow-Ups:
- Re: [RFC] nptl: change default stack guard size of threads
  - From: Wilco Dijkstra

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