Re: [Qemu-devel] [RESEND][PATCH 1.7] migration: drop MADVISE_DONT_NEED for incoming zero pages

2013-11-18 Thread Peter Lieven 

On 24.10.2013 11:14, Paolo Bonzini wrote:

Il 24/10/2013 08:21, Peter Lieven ha scritto:

Additionally we memmap target memory so it is essentially
zero initialized (except for e.g. option roms and bios which are loaded
into target memory although they shouldn't).

It was reported recently that this madvise causes a performance degradation
in some situations. As the madvise should only be called rarely and if it's 
called
it is likely on a busy page (it was non-zero and changed to zero during 
migration)
drop it completely.

Tagging this patch for 1.7.

has this been merged?

Peter

Re: [Qemu-devel] [RESEND][PATCH 1.7] migration: drop MADVISE_DONT_NEED for incoming zero pages

2013-11-18 Thread Paolo Bonzini 
Il 18/11/2013 13:48, Peter Lieven ha scritto:
 On 24.10.2013 11:14, Paolo Bonzini wrote:
 Il 24/10/2013 08:21, Peter Lieven ha scritto:
 Additionally we memmap target memory so it is essentially
 zero initialized (except for e.g. option roms and bios which are loaded
 into target memory although they shouldn't).

 It was reported recently that this madvise causes a performance
 degradation
 in some situations. As the madvise should only be called rarely and
 if it's called
 it is likely on a busy page (it was non-zero and changed to zero
 during migration)
 drop it completely.
 Tagging this patch for 1.7.
 has this been merged?

No.  Juan, can you prepare a quick pull request?

Paolo

Re: [Qemu-devel] [RESEND][PATCH 1.7] migration: drop MADVISE_DONT_NEED for incoming zero pages

2013-10-24 Thread Paolo Bonzini 
Il 24/10/2013 08:21, Peter Lieven ha scritto:
 Additionally we memmap target memory so it is essentially
 zero initialized (except for e.g. option roms and bios which are loaded
 into target memory although they shouldn't).
 
 It was reported recently that this madvise causes a performance degradation
 in some situations. As the madvise should only be called rarely and if it's 
 called
 it is likely on a busy page (it was non-zero and changed to zero during 
 migration)
 drop it completely.

Tagging this patch for 1.7.

Paolo