From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rik van Riel Subject: Re: [patch 0/6] Guest page hinting version 7. Date: Thu, 02 Apr 2009 15:06:31 -0400 Message-ID: <49D50CB7.2050705@redhat.com> References: <20090327150905.819861420@de.ibm.com> <200903281705.29798.rusty@rustcorp.com.au> <20090329162336.7c0700e9@skybase> <200904022232.02185.nickpiggin@yahoo.com.au> <20090402175249.3c4a6d59@skybase> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20090402175249.3c4a6d59@skybase> Sender: owner-linux-mm@kvack.org To: Martin Schwidefsky Cc: Nick Piggin , Rusty Russell , virtualization@lists.linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, virtualization@lists.osdl.org, akpm@osdl.org, frankeh@watson.ibm.com, hugh@veritas.com List-Id: virtualization@lists.linuxfoundation.org Martin Schwidefsky wrote: > The benefits are the same but the algorithmic complexity is reduced. > The patch to the memory management has complexity in itself but from a > 1000 feet standpoint guest page hinting is simpler, no? Page hinting has a complex, but well understood, mechanism and simple policy. Ballooning has a simpler mechanism, but relies on an as-of-yet undiscovered policy. Having experienced a zillion VM corner cases over the last decade and a bit, I think I prefer a complex mechanism over complex (or worse, unknown!) policy any day. > Ok, I can understand that. We probably need a KVM based version to show > that benefits exist on non-s390 hardware as well. I believe it can work for KVM just fine, if we keep the host state and the guest state in separate places (so the guest can always write the guest state without a hypercall). -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org