Re: Bug#605009: serious performance regression with ext4

[Jonathan Nieder <jrnieder@gmail.com>]

Hi Ted,

Ted Ts'o wrote:

> 1) Suppose package contains files "a", "b", and "c".  Which are you
> doing?
> 
> a)  extract a.dpkg-new ; fsync(a.dpkg-new); rename(a.dpkg-new, a);
>     extract b.dpkg-new ; fsync(b.dpkg-new); rename(b.dpkg-new, b);
>     extract c.dpkg-new ; fsync(c.dpkg-new); rename(c.dpkg-new, c);
> 
> or
> 
> b)  extract a.dpkg-new ; fsync(a.dpkg-new);
>     extract b.dpkg-new ; fsync(b.dpkg-new);
>     extract c.dpkg-new ; fsync(c.dpkg-new);
>     rename(a.dpkg-new, a);
>     rename(b.dpkg-new, b);
>     rename(c.dpkg-new, c);
> 
> or
> 
> c)  extract(a.dpkg-new);
>     extract(b.dpkg-new);
>     extract(c.dpkg-new);
>     fsync(a.dpkg-new);
>     fsync(b.dpkg-new);
>     fsync(c.dpkg-new);
>     rename(a.dpkg-new, a);
>     rename(b.dpkg-new, b);
>     rename(c.dpkg-new, c);
> 
> 
> (c) will perform the best for most file systems, including ext4.
[...]
> I am guessing you are doing (a) today --- am I right?  (c) or (d)
> would be best.

We are doing (c) today.

Regards,
Jonathan