Re: [PATCH v3] redir: Handle nested exec within REALLY_CLOSED redirection

[Martijn Dekker <martijn@xxxxxxxx>]

Op 16-01-19 om 22:39 schreef Martijn Dekker:
> Op 16-01-19 om 14:32 schreef Herbert Xu:
>> Thanks for the patch.  I took a deeper look into the history of
>> the bug and it turned out that I added REALLY_CLOSED as an
>> optimisation in order to avoid an unnecessary close(2) syscall.
> 
> Does this actually save cycles? I'm probably missing something, but that
> code looks to me like it probably uses more cycles than close(2) going
> 'descriptor not open, return'.

Never mind, stupid question that I should have googled before asking it.
The answer is that a switch to kernel mode and back is expensive.

- M.