Re: [PATCHv4 6/6] x86/signal: add SA_{X32,IA32}_ABI sa_flags

From	Oleg Nesterov <oleg@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [PATCHv4 6/6] x86/signal: add SA_{X32,IA32}_ABI sa_flags
Date	2016-09-01 23:20 +0200
Message-ID	<scHyW-75a-1@gated-at.bofh.it> (permalink)
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On 09/01, Dmitry Safonov wrote:
>
> And the biggest problem in this approach would be not the size of
> code changes to CRIU (which are already quite large with this
> patches set), but AFAICS, it will have big performance penalty:
> we would need to bounce process tree, processes properties
> from parent-CRIU to child-CRIU after exec() call and down on
> the processes hierarchy, recreating processes while synchronizing
> process's data from images.
>
> As for now, we already have time-critical problems in СRIU and
> we try to reduce the number of system calls, while it's still slow
> at some places. But that approach will lead to:
> o exec different CRIU
> o initialize it (i.e, parse /proc/self/maps to know it's vmas)
> o transphere process tree, for each process it's properties with IPC
>    after exec()
> It will all go for a large number of syscalls in total.

I do not really understand why it has to be so complicated, but
I can be easily wrong.

> And this arch_prctl() API is visible under CHECKPOINT_RESTORE
> config option, so will not bother anyone.

I mostly dislike 6/6. This new feauture looks a bit strange to me.

Nevermind, let me repeat once again, I am not trying to argue with
this series. No objections from me.

Oleg.

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Re: [PATCHv4 6/6] x86/signal: add SA_{X32,IA32}_ABI sa_flags Dmitry Safonov <0x7f454c46@gmail.com> - 2016-08-31 16:10 +0200
  Re: [PATCHv4 6/6] x86/signal: add SA_{X32,IA32}_ABI sa_flags Oleg Nesterov <oleg@redhat.com> - 2016-09-01 14:40 +0200
    Re: [PATCHv4 6/6] x86/signal: add SA_{X32,IA32}_ABI sa_flags Cyrill Gorcunov <gorcunov@gmail.com> - 2016-09-01 14:50 +0200
      Re: [PATCHv4 6/6] x86/signal: add SA_{X32,IA32}_ABI sa_flags Dmitry Safonov <0x7f454c46@gmail.com> - 2016-09-01 15:50 +0200
        Re: [PATCHv4 6/6] x86/signal: add SA_{X32,IA32}_ABI sa_flags Cyrill Gorcunov <gorcunov@gmail.com> - 2016-09-01 16:00 +0200
        Re: [PATCHv4 6/6] x86/signal: add SA_{X32,IA32}_ABI sa_flags Oleg Nesterov <oleg@redhat.com> - 2016-09-01 23:20 +0200

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