Patch: improve huge page support

[Andrew Haley]

On 05/04/2011 04:53 PM, Dr Andrew John Hughes wrote:
> On 15:49 Wed 04 May     , Andrew Haley wrote:
>> My big patch to improve huge page support in now in HotSpot upstream.
>> This is a backport.
>>
>> The question is: to what branches should we apply this?  It makes the
>> use of huge pages much, much easier.  You no longer need root access
>> for anything except setting the size of the huge page pool, and the
>> huge pages aren't locked in memory, so it's a big improvement for
>> usability.  If the new huge page support doesn't work in the kernel,
>> it falls back to the old SysV-style huge page allocator.
>>
>> Thoughts?
>>
> 
> I notice this doesn't actually enable the patch in the Makefile.am.  Have
> you built this on any version of IcedTea yet?

Yes, but it's missing from the email, that's all.

> I would prefer that this was two separate patches, corresponding to each
> upstream changeset.  It makes it easier to just delete the patch file
> when it gets backported upstream in OpenJDK6 (and, prior to that, makes
> it easier to see what we need to request for backport).

The patches aren't separate, and shouldn't be applied separately.  There
are no circumstances in which it's appropriate to apply just one, IMO.

> As to branches, things could get tricky, as each of the currently supported
> branches has two HotSpot variants as follows:
> 
> 1.8: hs14 & hs16
> 1.9: hs17 (default) & hs19
> 1.10: hs19 (default) & hs20
> 1.11 (HEAD): hs19 & hs20 (default)
> 
> So that's potentially five versions of HotSpot to patch (hs14, hs16, hs17, hs19, hs20)
> but it may be that this code has changed little and the same patch can be applied to
> several versions.

I suspect so, but I had to do a fair bit of work on the backport,
as this file has some churn.

> 1.8 is due to become obsolete when we ship 1.11 (according to our 3-release policy [1]),
> but that won't be until July and there will be a security update before that on the 7th
> of June [2].
> 
> So I'll leave the call on 1.8 to you, but I'd expect we at least want this in 1.9,
> 1.10 and HEAD.
> 
> 1. http://mail.openjdk.java.net/pipermail/distro-pkg-dev/2011-March/013215.html
> 2. http://www.oracle.com/technetwork/topics/security/alerts-086861.html

OK, I see.

Andrew.