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Re: [PATCH] On Hurd, don't use not implemented madvise()
From: |
tomas |
Subject: |
Re: [PATCH] On Hurd, don't use not implemented madvise() |
Date: |
Sat, 3 Jun 2017 08:41:32 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
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On Fri, Jun 02, 2017 at 10:00:18PM -0400, Mark H Weaver wrote:
> <address@hidden> writes:
[...]
> > This would at least suggest having a way to query whether madvise is
> > available, through some introspection (giving the program a chance
> > to adapt its behavior)?
>
> First of all, you should read this for background:
>
> https://wingolog.org/archives/2014/03/17/stack-overflow
Done.
> If you've done that, then you should understand that this new feature in
> guile-2.2 fundamentally changes the way we can express loops in Scheme
> that build recursive data structures where scalability is important.
[...]
Yes, I got that: in a nutshell, getting the stack auto-extended instead
of being blown out of existence by a segfault or similar.
> Consider how frequently patterns like this occur. Do you really want to
> duplicate every piece of code with a loop of this form? It would be
> better to just give up on this new feature entirely.
>
> Anyway, even if you did duplicate your code, that would not solve the
> problem, because many procedures in Guile itself are now written in the
> nicer way to take advantage of this. One such example is 'map'.
You are right, duplicating every piece of code doesn't seem to be
a Good Thing.
I rather proposed the introspection for those who want to come up
with whatever other ideas: it might be they'll want to warn the user
right off at the beginning ("uh, oh: no madvise: expect a rough ride",
so they can then segfault without guilt :)
> I'm quite fond of the Hurd design, and I hope it continues to grow, but
> it's unrealistic to expect developers to write loops like this in a
> fundamentally less clear way to cater to an experimental OS that has so
> few users.
>
> Does that make sense?
It does. As I said, I just proposed that, if Guile decides to use
madvise() dynamically (by "bypassing" ENOSYS -- that's IMO a good idea
anyway), it should give the user a possibility to check for that very
fact ("do we, actually, have an madvise()?"). WDYT?
Cheers
- -- tomás
>
> Mark
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- Re: [PATCH] On Hurd, don't use not implemented madvise(), Manolis Ragkousis, 2017/06/01
- Re: [PATCH] On Hurd, don't use not implemented madvise(), Mark H Weaver, 2017/06/01
- Re: [PATCH] On Hurd, don't use not implemented madvise(), tomas, 2017/06/02
- Re: [PATCH] On Hurd, don't use not implemented madvise(), Mark H Weaver, 2017/06/02
- Re: [PATCH] On Hurd, don't use not implemented madvise(),
tomas <=
- Efficiency of `map` (was: [PATCH] On Hurd, don't use not implemented madvise()), Stefan Monnier, 2017/06/08
- Re: Efficiency of `map`, Mark H Weaver, 2017/06/10
- Re: Efficiency of `map`, Nala Ginrut, 2017/06/10
- Re: Efficiency of `map`, Mark H Weaver, 2017/06/11