* David Miller <davem@xxxxxxxxxxxxx> wrote: > From: Ingo Molnar <mingo@xxxxxxx> > Date: Wed, 18 Feb 2009 12:01:44 +0100 > > > * David Miller <davem@xxxxxxxxxxxxx> wrote: > > > > | Introduce mod_timer_noact() which for example is to replace > > | the calls to del_timer()/add_timer() in > > | __nf_ct_refresh_acct(). It works like mod_timer() but doesn't > > | activate or modify the timeout of an inactive timer which is > > | the behaviour we want in order to be able to use timers as a > > | means of synchronization in nf_conntrack. > > > > It does not mention the overhead to the regular timer interfaces > > at all, nor does it explain the reasons for this change > > adequately. > > You (conveniently) skipped this part of his commit message, so > I guess this is the part you didn't read very carefully: > > A later patch will modify __nf_ct_refresh_acct() to use > mod_timer_noact() which will then save one spin_lock_irqsave() > / spin_lock_irqrestore() pair per conntrack timer update. This > will also get rid of the race we currently have without adding > more locking in nf_conntrack. > > The whole point is to avoid two spin_lock_irqsave() sequences, thus > taking the timer locks twice. > > So Ingo, when you say in response: > > Why don't you use? > > if (del_timer()) > add_timer(); > > you really look foolish and, in fact, disrespectful to Stephen. > > This was my objection to your email, it proved that you didn't > really read his changelog message. He explained perfectly well > what the final goal was of his changes. > > And you have this knee-jerk reaction quite often. You accusing me of knee-jerk reaction is the joke of the century ;-) Anyway, it's all handled, you just need to read the rest of the thread. Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
