From: Stephen Hemminger <shemminger@osdl.org>
To: Ben Greear <greearb@candelatech.com>
Cc: Ravikiran G Thirumalai <kiran@scalex86.org>,
Andrew Morton <akpm@osdl.org>,
linux-kernel@vger.kernel.org, dipankar@in.ibm.com,
bharata@in.ibm.com, shai@scalex86.org,
Rusty Russell <rusty@rustcorp.com.au>,
netdev@vger.kernel.org, davem@davemloft.net
Subject: Re: [patch 7/11] net: Use bigrefs for net_device.refcount
Date: Tue, 13 Sep 2005 09:46:12 -0700 [thread overview]
Message-ID: <20050913094612.7e8d611b@localhost.localdomain> (raw)
In-Reply-To: <4326FFC2.7030803@candelatech.com>
On Tue, 13 Sep 2005 09:35:14 -0700
Ben Greear <greearb@candelatech.com> wrote:
> Stephen Hemminger wrote:
> > On Tue, 13 Sep 2005 09:10:12 -0700
> > Ravikiran G Thirumalai <kiran@scalex86.org> wrote:
> >
> >
> >>The net_device has a refcnt used to keep track of it's uses.
> >>This is used at the time of unregistering the network device
> >>(module unloading ..) (see netdev_wait_allrefs) .
> >>For loopback_dev , this refcnt increment/decrement is causing
> >>unnecessary traffic on the interlink for NUMA system
> >>affecting it's performance. This patch improves tbench numbers by 6% on a
> >>8way x86 Xeon (x445).
> >>
> >
> >
> > Since when is bringing a network device up/down performance critical?
>
> We grab and drop a reference for each poll of a device, roughly.
>
> See dev_hold in _netif_rx_schedule(struct net_device *dev)
> in include/netdevice.h, for instance.
Yeah, that would be an issue, especially since the rest of that
path is nicely per-cpu
next prev parent reply other threads:[~2005-09-13 16:46 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20050913155112.GB3570@localhost.localdomain>
2005-09-13 16:10 ` [patch 7/11] net: Use bigrefs for net_device.refcount Ravikiran G Thirumalai
2005-09-13 16:26 ` Stephen Hemminger
2005-09-13 16:35 ` Ben Greear
2005-09-13 16:46 ` Stephen Hemminger [this message]
2005-09-13 20:26 ` David S. Miller
2005-09-13 22:16 ` Ravikiran G Thirumalai
2005-09-13 18:27 ` Eric Dumazet
2005-09-13 18:53 ` Ravikiran G Thirumalai
2005-09-13 16:12 ` [patch 8/11] net: dst_abstraction macros Ravikiran G Thirumalai
2005-09-13 16:17 ` [patch 9/11] net: dst_entry.refcount, use, lastuse to use alloc_percpu Ravikiran G Thirumalai
2005-09-13 20:24 ` David S. Miller
2005-09-13 22:07 ` Ravikiran G Thirumalai
2005-09-13 22:12 ` David S. Miller
2005-09-13 23:17 ` Ravikiran G Thirumalai
2005-09-13 23:27 ` David S. Miller
2005-09-14 7:21 ` Rusty Russell
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