> On Fri, Jun 2, 2017 at 8:35 AM, Jerome Glisse <jglisse@xxxxxxxxxx> wrote: > > On Wed, May 31, 2017 at 01:59:54PM +1000, Balbir Singh wrote: > >> On Wed, 24 May 2017 13:20:21 -0400 > >> Jérôme Glisse <jglisse@xxxxxxxxxx> wrote: > >> > >> > This patch add a new memory migration helpers, which migrate memory > >> > backing a range of virtual address of a process to different memory > >> > (which can be allocated through special allocator). It differs from > >> > numa migration by working on a range of virtual address and thus by > >> > doing migration in chunk that can be large enough to use DMA engine > >> > or special copy offloading engine. > >> > > >> > Expected users are any one with heterogeneous memory where different > >> > memory have different characteristics (latency, bandwidth, ...). As > >> > an example IBM platform with CAPI bus can make use of this feature > >> > to migrate between regular memory and CAPI device memory. New CPU > >> > architecture with a pool of high performance memory not manage as > >> > cache but presented as regular memory (while being faster and with > >> > lower latency than DDR) will also be prime user of this patch. > >> > > >> > Migration to private device memory will be useful for device that > >> > have large pool of such like GPU, NVidia plans to use HMM for that. > >> > > >> > >> It is helpful, for HMM-CDM however we would like to avoid the downsides > >> of MIGRATE_SYNC_NOCOPY > > > > What are the downside you are referring too ? > > IIUC, MIGRATE_SYNC_NO_COPY is for anonymous memory only. It can migrate anything, file back page too. It just forbid that latter case if it is ZONE_DEVICE HMM. I should have time now to finish the CDM patchset and i will post, previous patches already enabled file back page migration for HMM-CDM. The NOCOPY is for no CPUCOPY, i couldn't think of a better name. Cheers, Jérôme -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href
