[CRIU] [PATCH 4/5] kdat: Cache kdat object into /run/criu.kdat (v3)

[Dmitry Safonov]

On 04/27/2017 05:58 PM, Pavel Emelyanov wrote:
> Doing kerndat checks on every criu start is way too slow. We
> need some way to speed this checks up on a particular box.
> 
> As suggested by Andre, Dima and Mike let's try to keep the
> collected kdat bits into some tmpfs file. Keeping it on
> tmpfs would invaludate this cache on every machine reboot.
> 
> There have been many suggestions how to generate this file,
> my proposal is to create it once the kdat object is filled
> by criu, w/o any explicit command. Optionally we can add
> 'criu kdat --save|--drop' actions to manage this file.
> 
> v2:
> * don't ignore return code of write() (some glibcs complain)
> * unlink tmp file in case rename failed
> 
> v3:
> * add one more magic into kerndat_s which is the 'date +%s'
> * ignore any errors opening or saving cache. Only size/magic
>    mismatch matters (and result in dropping the cache)
> * cache file path is Makefile-configurable (RUNDIR)
> * don't save cache if kerndat auto-detection failed
> 
> Signed-off-by: Pavel Emelyanov <xemul at virtuozzo.com>

Reviewed-by: Dmitry Safonov <dsafonov at virtuozzo.com>

There is still one nit below, heh.

> ---
>   Makefile.install       |  3 +-
>   criu/Makefile.crtools  |  1 +
>   criu/include/kerndat.h |  1 +
>   criu/include/magic.h   |  6 ++++
>   criu/kerndat.c         | 85 ++++++++++++++++++++++++++++++++++++++++++++++++++
>   5 files changed, 95 insertions(+), 1 deletion(-)
> 
> diff --git a/Makefile.install b/Makefile.install
> index f1e5415..ddde93d 100644
> --- a/Makefile.install
> +++ b/Makefile.install
> @@ -7,6 +7,7 @@ MANDIR		:= $(PREFIX)/share/man
>   LIBDIR		:= $(PREFIX)/lib
>   INCLUDEDIR	:= $(PREFIX)/include
>   LIBEXECDIR	:= $(PREFIX)/libexec
> +RUNDIR		:= /run

An optional nit: if this will be
RUNDIR		?= /run
then package maintainer will not need a patch to correct this according
to distribution and just will need to run `make RUNDIR=<...>`

-- 
              Dmitry