Linux-Wireless Archive on lore.kernel.org
 help / Atom feed
From: Johannes Berg <johannes@sipsolutions.net>
To: Ben Greear <greearb@candelatech.com>, linux-wireless@vger.kernel.org
Subject: Re: [PATCH-v3 1/2] wireless: Support assoc-at-ms timer in sta-info
Date: Fri, 14 Jun 2019 20:46:40 +0200
Message-ID: <231c9afd2aaca99c89bc73954307a28a60e86d18.camel@sipsolutions.net> (raw)
In-Reply-To: <7d606df7-bb8e-c454-1eaf-24fd454eab8e@candelatech.com>

On Fri, 2019-06-14 at 08:14 -0700, Ben Greear wrote:
> 
> 
> So, maybe I return instead the elapsed time in the netlink API instead of a
> timestamp.  I think that will give me the value that I am looking for,
> and I can still print out the 'real' time in iw so any tools reading that
> output and do some simple math and figure out the 'real' associated-at time.

I don't think that's good. There's a delay between filling the message
and then processing it in userspace. We had this in the scan code and
learned that was full of races.

The better thing is to use CLOCK_BOOTTIME nanoseconds, and then
userspace can use clock_gettime() to get the current time etc. and then
do whatever calculations it needs. If it wants to print the realtime
timestamp, it could even calculate that (with some jitter) by doing
clock_gettime() on both realtime and boottime clocks...

johannes


      reply index

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-15 17:21 greearb
2019-04-15 17:21 ` [PATCH-v3 2/2] mac80211: add assoc-at-ms support greearb
2019-06-12 22:53   ` Ben Greear
2019-06-14 13:38 ` [PATCH-v3 1/2] wireless: Support assoc-at-ms timer in sta-info Johannes Berg
2019-06-14 14:46   ` Ben Greear
2019-06-14 14:56     ` Johannes Berg
2019-06-14 15:14       ` Ben Greear
2019-06-14 18:46         ` Johannes Berg [this message]

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=231c9afd2aaca99c89bc73954307a28a60e86d18.camel@sipsolutions.net \
    --to=johannes@sipsolutions.net \
    --cc=greearb@candelatech.com \
    --cc=linux-wireless@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-Wireless Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-wireless/0 linux-wireless/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-wireless linux-wireless/ https://lore.kernel.org/linux-wireless \
		linux-wireless@vger.kernel.org linux-wireless@archiver.kernel.org
	public-inbox-index linux-wireless


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-wireless


AGPL code for this site: git clone https://public-inbox.org/ public-inbox