[CRIU] [PATCH] ptrace: Skip GETREGS on exits from syscalls when possible

[Pavel Emelyanov]

On 09/16/2014 12:24 PM, Cyrill Gorcunov wrote:
> On Tue, Sep 16, 2014 at 12:27:07AM +0400, Pavel Emelyanov wrote:
>> From: Pavel Emelyanov <xemul at parallels.com>
>>
>> The PTRACE_SYSCALL traps task twice -- first on enter into
>> and then on exit from syscall. If we trace a single task (and
>> we do it on dump two times per task) we may skip half of all
>> getregs calls -- on exit we don't need them.
>>
>> Signed-off-by: Pavel Emelyanov <xemul at parallels.com>
> 
> Does it really saves us that much time so that we sacrifice logging?

We don't. The aim is to remove unneeded PTRACE_GETREGS calls.

> Previously we always check that we're in good shape and log out
> the syscall engine is about to yield. Thus I'm not sure if it
> worth it (patch looks good though, I simply have a gut feeling
> that one day we might hit some problem with it).
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