[lkml]   [2005]   [Oct]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH 0/4] Swap migration V3: Overview
Andrew Morton wrote:
> Christoph Lameter <> wrote:
>>Page migration is also useful for other purposes:
>> 1. Memory hotplug. Migrating processes off a memory node that is going
>> to be disconnected.
>> 2. Remapping of bad pages. These could be detected through soft ECC errors
>> and other mechanisms.
> It's only useful for these things if it works with close-to-100% reliability.
> And there are are all sorts of things which will prevent that - mlock,
> ongoing direct-io, hugepages, whatever.
In lhms tree, current status is below: (If I'm wrong, plz fix)
For mlock, direct page migration will work fine. try_to_unmap_one()
in -mhp tree has an argument *force* and ignore VM_LOCKED, it's for this.

For direct-io, we have to wait for completion.
The end of I/O is not notified and memory_migrate() is just polling pages.

For hugepages, we'll need hugepage demand paging and more work, I think.

When a process migrates to other nodes by hand, it can cooperate with migration
subsystem. So we don't have to be afraid of some special using of memory, in many case.
I think Christoph's approach will work fine.

When it comes to memory-hotplug, arbitrary processes are affected.
It's more difficult.

We should focus on 'process migraion on demand', in this thread.

-- Kame

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-10-21 08:06    [W:0.157 / U:0.308 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site