Re: [PATCH] powerpc/powernv: Increase memory block size to 1GB on radix

2017-09-09 Thread Michael Ellerman
We should do the 1G block size as a fix, and backport it, and then make the hot unplug code smarter. cheers On 8 September 2017 11:15:47 am AEST, Anton Blanchard wrote: >Hi Reza, > >> I may be misunderstanding this, but what if we did something like x86 > >> does? When trying

Re: [PATCH] powerpc/powernv: Increase memory block size to 1GB on radix

2017-09-08 Thread Balbir Singh
On Thu, Sep 7, 2017 at 5:21 PM, Benjamin Herrenschmidt wrote: > On Thu, 2017-09-07 at 15:17 +1000, Anton Blanchard wrote: >> Hi, >> >> > There is a similar issue being worked on w.r.t pseries. >> > >> >

Re: [PATCH] powerpc/powernv: Increase memory block size to 1GB on radix

2017-09-07 Thread Anton Blanchard
Hi Reza, > I may be misunderstanding this, but what if we did something like x86 > does? When trying to unplug a region smaller than the mapping, they > fill that part of the pagetable with 0xFD instead of freeing the > whole thing. Once the whole thing is 0xFD, free it. > > See

Re: [PATCH] powerpc/powernv: Increase memory block size to 1GB on radix

2017-09-07 Thread Reza Arbab
On Thu, Sep 07, 2017 at 05:17:41AM +, Anton Blanchard wrote: But all of memory on PowerNV should be able to be hot unplugged, so there are two options as I see it - either increase the memory block size, or map everything with 2MB pages. I may be misunderstanding this, but what if we did

Re: [PATCH] powerpc/powernv: Increase memory block size to 1GB on radix

2017-09-07 Thread Benjamin Herrenschmidt
On Thu, 2017-09-07 at 15:17 +1000, Anton Blanchard wrote: > Hi, > > > There is a similar issue being worked on w.r.t pseries. > > > > https://lkml.kernel.org/r/1502357028-27465-1-git-send-email-bhar...@linux.vnet.ibm.com > > > > The question is should we map these regions ? ie, we need to tell

Re: [PATCH] powerpc/powernv: Increase memory block size to 1GB on radix

2017-09-06 Thread Anton Blanchard
Hi, > There is a similar issue being worked on w.r.t pseries. > > https://lkml.kernel.org/r/1502357028-27465-1-git-send-email-bhar...@linux.vnet.ibm.com > > The question is should we map these regions ? ie, we need to tell the > kernel memory region that we would like to hot unplug later so

Re: [PATCH] powerpc/powernv: Increase memory block size to 1GB on radix

2017-09-06 Thread Aneesh Kumar K.V
On 09/07/2017 10:35 AM, Anton Blanchard wrote: From: Anton Blanchard Memory hot unplug on PowerNV radix hosts is broken. Our memory block size is 256MB but since we map the linear region with very large pages, each pte we tear down maps 1GB. A hot unplug of one 256MB memory

[PATCH] powerpc/powernv: Increase memory block size to 1GB on radix

2017-09-06 Thread Anton Blanchard
From: Anton Blanchard Memory hot unplug on PowerNV radix hosts is broken. Our memory block size is 256MB but since we map the linear region with very large pages, each pte we tear down maps 1GB. A hot unplug of one 256MB memory block results in 768MB of memory getting