Re: [PATCH iproute2 v4 3/4] ifstat: Add 64 bits based stats to extended statistics

On Thu, 19 Jan 2017 08:06:21 -0800
Roopa Prabhu [off-list ref] wrote:

On 1/19/17, 7:21 AM, Nogah Frankel wrote:

quoted

quoted

-----Original Message-----
From: Nogah Frankel
Sent: Sunday, January 15, 2017 3:55 PM
To: 'Stephen Hemminger' <stephen@networkplumber.org>
Cc: netdev@vger.kernel.org; roszenrami@gmail.com; roopa@cumulusnetworks.com; Jiri
Pirko [off-list ref]; Ido Schimmel [off-list ref]; Elad Raz
[off-list ref]; Yotam Gigi [off-list ref]; Or Gerlitz
[off-list ref]
Subject: RE: [PATCH iproute2 v4 3/4] ifstat: Add 64 bits based stats to extended statistics


 

quoted

-----Original Message-----
From: Stephen Hemminger [mailto:stephen@networkplumber.org]
Sent: Friday, January 13, 2017 3:44 AM
To: Nogah Frankel <redacted>
Cc: netdev@vger.kernel.org; roszenrami@gmail.com; roopa@cumulusnetworks.com;  

Jiri  

quoted

Pirko [off-list ref]; Ido Schimmel [off-list ref]; Elad Raz
[off-list ref]; Yotam Gigi [off-list ref]; Or Gerlitz
[off-list ref]
Subject: Re: [PATCH iproute2 v4 3/4] ifstat: Add 64 bits based stats to extended statistics

On Thu, 12 Jan 2017 15:49:50 +0200
Nogah Frankel [off-list ref] wrote:
 

quoted

The default stats for ifstat are 32 bits based.
The kernel supports 64 bits based stats. (They are returned in struct
rtnl_link_stats64 which is an exact copy of struct rtnl_link_stats, in
which the "normal" stats are returned, but with fields of u64 instead of
u32). This patch adds them as an extended stats.

It is read with filter type IFLA_STATS_LINK_64 and no sub type.

It is under the name 64bits
(or any shorten of it as "64")

For example:
ifstat -x 64bit

Signed-off-by: Nogah Frankel <redacted>
Reviewed-by: Jiri Pirko <redacted>  

Other commands (like ip link) always use the 64 bit statistics if available
from the device. I see no reason that ifstat needs to be different.
 

Do you mean to change the default ifstat results to be 64 bits based?
I tried it in the first version, but Roopa commented that it was not a good idea.
She said they tried it in the past and it caused backward compatibilities problems.
(Or maybe I didn't understand correctly)  

So, can I leave the default ifstat results to be 32 bits based, for the time being?
 

From past discussions: Moving the default to 64bit has compat issues with the old history file.
There is a way to make it work by using a new file header (to indicate that it is 64 bit) in
a freshly created history file and also check this header before dumping stats into the history file.
ie maintain backward compat without introducing a new option. It is doable.

One approach is, you can drop the 64bit option from this series and
try updating the default to 64 bit (with compat handling code) in a later series.

The ifstat code could do conversion based on file size.

  if (history_file_is_32bit()) {
	printf("converting to 64 bit format\n");
        ...
  }