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Re: patch to support output synchronization under -j
From: |
David Boyce |
Subject: |
Re: patch to support output synchronization under -j |
Date: |
Fri, 15 Apr 2011 12:39:56 -0400 |
On Fri, Apr 15, 2011 at 11:09 AM, Eli Zaretskii <address@hidden> wrote:
> But this new option uses up 2 additional files per job, doesn't it?
One or two, as discussed elsewhere in this thread.
> Each sub-Make inherits all the file descriptors of all its parents,
> grandparents, etc. If a sub-Make was launched when 4 other jobs were
> running in parallel, the sub-Make will inherit 8 file descriptors that
> it won't use. The deeper the recursion, the more inherited
> descriptors.
You have a good point. I should probably turn on FD_CLOEXEC for these.
> What about people who use "make -j" without limits?
As noted, those people are at risk of exhausting many resources.
> It's not like having a 256-core machine is a fantasy that will not
> happen in a few years. On my day job, we are already using 12 cores
> and don't consider that "living on the edge".
Right, but my point was the limits of which I speak are old. I don't
think a 256-core processor will ever run on a kernel from the 1980's.
Or in other words, part of scaling an OS to many cores involves
removing or at least upping artificial resource constraints. The
natural trend toward 64-bit systems is part of that of course.
> I think the real kernel limitation, if there is one, is on file
> descriptors, not FILE objects. The latter live in the application.
On that you are wrong, at least WRT POSIX machines. The old limit on
streams was a function of an 8-bit field in the FILE structure,
whereas every system I've ever used can allocate at least 1024
descriptors.
David
- Re: patch to support output synchronization under -j, (continued)
- Re: patch to support output synchronization under -j, David Boyce, 2011/04/14
- Re: patch to support output synchronization under -j, Eli Zaretskii, 2011/04/15
- Re: patch to support output synchronization under -j, Tim Murphy, 2011/04/15
- Re: patch to support output synchronization under -j, Eli Zaretskii, 2011/04/15
- Re: patch to support output synchronization under -j, Stefano Lattarini, 2011/04/15
- Re: patch to support output synchronization under -j, David Boyce, 2011/04/15
- Re: patch to support output synchronization under -j, Eli Zaretskii, 2011/04/15
- Re: patch to support output synchronization under -j, David Boyce, 2011/04/15
- Re: patch to support output synchronization under -j, Eli Zaretskii, 2011/04/15
- Re: patch to support output synchronization under -j, Paul Smith, 2011/04/15
- Re: patch to support output synchronization under -j,
David Boyce <=
- Re: patch to support output synchronization under -j, Eli Zaretskii, 2011/04/15
- Re: patch to support output synchronization under -j, Tim Murphy, 2011/04/15
- Re: patch to support output synchronization under -j, Paul Smith, 2011/04/15
- Re: patch to support output synchronization under -j, Eli Zaretskii, 2011/04/15
- Re: patch to support output synchronization under -j, Edward Welbourne, 2011/04/19
- Re: patch to support output synchronization under -j, David Boyce, 2011/04/19
- Re: patch to support output synchronization under -j, Howard Chu, 2011/04/15
- Re: patch to support output synchronization under -j, Tim Murphy, 2011/04/15
- Re: patch to support output synchronization under -j, David Boyce, 2011/04/14
- Re: patch to support output synchronization under -j, Paul Smith, 2011/04/14