Arjan van de Ven <[email protected]> writes:
> On Sun, 2007-07-15 at 19:17 +0200, Bodo Eggert wrote:
>> Matt Mackall <[email protected]> wrote:
>> > On Fri, Jul 13, 2007 at 03:20:54PM +0200, Rene Herman wrote:
>>
>> >> As far as I'm aware, the actual reason for 4K stacks is that after the
>> >> system has been up and running for some time getting "1 physically
>> >> contiguous pages" becomes significantly easier than 2 which wouldn't be
>> >> arbitrary.
>> >
>> > If there are exactly two free pages in the system, the odds of them
>> > being buddies (ie adjacent AND properly aligned) is quite small. The
>> > available page pool has to grow quite a bit before the availability of
>> > order-1 page pairs approaches 100%.
>>
>> If there are exactly two free pages in a system, the odds of starting any
>> program are not very good. You'll have to swap, and if you do, you can swap
>> two more pages in order to free enough RAM for the stack.
>
> even if you have several thousand pages the odds aren't good; or rather,
> they start out reasonably ok until something starts eating very
> deliberately at the 8k pages pool, for example the new app creating
> about 10 threads....
>
> The 4K issue is "tricky", only a few selected workload/compiler combos
> seem to hit the dirt, yet distros like Fedora and RHEL use 4K stacks
> since forever, and if it gave massive problems they wouldn't do that.
> On the upside, especially on very-threaded workloads, it helps
> reliability and the VM a lot...
I guess no Fedora users run md+lvm+xfs then. That combination has
quite reliably crashed any 4k-stack kernel I've ever cared to try.
--
Måns Rullgård
[email protected]
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
