From: Stefan Rompf <stefan@loplof.de>
To: "David S. Miller" <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Subject: Re: [PATCH] core: linkwatch should use jiffies64
Date: Mon, 8 May 2006 20:28:56 +0200 [thread overview]
Message-ID: <200605082028.57328.stefan@loplof.de> (raw)
In-Reply-To: <20060507.230727.67882043.davem@davemloft.net>
Am Montag 08 Mai 2006 08:07 schrieb David S. Miller:
> What is so special about what linkwatch is doing such
> that it needs this kind of treatment and other similar
> pieces or code do not?
>
> We have all sorts of interfaces such as time_after() et el.
> in order to deal with wrapping issues.
time_after() and friends can handle jiffies wrapping, however they require the
difference between compared times to be less than 0x80000000 jiffies (about
24 days on HZ=1000) to work reliably on 32bit architectures. So if the
network is stable for 24 days, events generated within days 25-49 will suffer
a *huge* false delay.
> And furthermore
> using 64-bit jiffies here might not be appropriate because
> they are not guarenteed to be accessed atomically,
get_jiffies_64() handles this transparently.
Stefan
next prev parent reply other threads:[~2006-05-08 18:28 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-07 10:13 [PATCH] core: linkwatch should use jiffies64 Stefan Rompf
2006-05-08 6:07 ` David S. Miller
2006-05-08 18:28 ` Stefan Rompf [this message]
2006-05-09 11:26 ` [NET] linkwatch: Handle jiffies wrap-around Herbert Xu
2006-05-09 16:51 ` Stefan Rompf
2006-05-09 22:28 ` David S. Miller
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