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From: Paul Brook <paul@codesourcery.com>
To: qemu-devel@nongnu.org
Cc: Andrea Arcangeli <aarcange@redhat.com>, Avi Kivity <avi@redhat.com>
Subject: Re: [Qemu-devel] [PATCH QEMU] transparent hugepage support
Date: Thu, 11 Mar 2010 16:28:04 +0000	[thread overview]
Message-ID: <201003111628.04566.paul@codesourcery.com> (raw)
In-Reply-To: <4B9911B0.5000302@redhat.com>

> > +		/*
> > +		 * Align on HPAGE_SIZE so "(gfn ^ pfn)&
> > +		 * (HPAGE_SIZE-1) == 0" to allow KVM to take advantage
> > +		 * of hugepages with NPT/EPT.
> > +		 */
> > +		new_block->host = qemu_memalign(1<<  TARGET_HPAGE_BITS, size);

This should not be target dependent. i.e. it should be the host page size.

> That is a little wasteful.  How about a hint to mmap() requesting proper
> alignment (MAP_HPAGE_ALIGN)?

I'd kinda hope that we wouldn't need to. i.e. the host kernel is smart enough 
to automatically align large allocations anyway.

This is probably a useful optimization regardless of KVM.

Paul

  parent reply	other threads:[~2010-03-11 16:32 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-03-11 15:14 [Qemu-devel] [PATCH QEMU] transparent hugepage support Andrea Arcangeli
2010-03-11 15:52 ` Avi Kivity
2010-03-11 16:05   ` Andrea Arcangeli
2010-03-13  8:28     ` Avi Kivity
2010-03-13 17:47       ` Andrea Arcangeli
2010-03-11 16:28   ` Paul Brook [this message]
2010-03-11 16:46     ` Andrea Arcangeli
2010-03-11 17:55       ` Paul Brook
2010-03-11 18:49         ` Andrea Arcangeli
2010-03-12 11:36           ` Paul Brook
2010-03-12 14:52             ` Andrea Arcangeli
2010-03-12 16:04               ` Paul Brook
2010-03-12 16:17                 ` Andrea Arcangeli
2010-03-12 16:24                   ` Paul Brook
2010-03-12 16:57                     ` Andrea Arcangeli
2010-03-12 17:10                       ` Paul Brook
2010-03-12 17:41                         ` Andrea Arcangeli
2010-03-12 18:17                           ` Paul Brook
2010-03-12 18:36                             ` Andrea Arcangeli
2010-03-12 18:41                               ` Paul Brook
2010-03-12 18:51                                 ` Andrea Arcangeli
2010-03-12 22:40                                   ` Jamie Lokier
2010-03-12 16:10               ` Paul Brook

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