From: Eric Dumazet <eric.dumazet@gmail.com>
To: David Miller <davem@davemloft.net>
Cc: stephen@networkplumber.org, netdev@vger.kernel.org,
sthemmin@microsoft.com
Subject: Re: [PATCH] inet: add bound ports statistic
Date: Wed, 28 Feb 2018 20:28:15 -0800 [thread overview]
Message-ID: <1519878495.11536.4.camel@gmail.com> (raw)
In-Reply-To: <20180228.223217.1178910703084049513.davem@davemloft.net>
On Wed, 2018-02-28 at 22:32 -0500, David Miller wrote:
> From: Eric Dumazet <eric.dumazet@gmail.com>
> Date: Wed, 28 Feb 2018 18:28:02 -0800
>
> > How useful it is to report this information ?
> >
> > Given REUSEADDR and REUSEPORT, I really wonder what can be derived from
> > this counter.
> >
> > It seems its semantic is weak.
>
> To me none of this really matters.
>
> What matters is that iproute2 reported this via slabinfo for longer
> than a decade.
>
> It broke recently when SLAB started merging caches just like SLUB
> always did.
Linus himself removed some info that was much more useful in
commit a5ad88ce8c7fae7d ("mm: get rid of 'vmalloc_info' from
/proc/meminfo")
# egrep "VmallocUsed|VmallocChunk" /proc/meminfo
VmallocUsed: 0 kB
VmallocChunk: 0 kB
So I vote for not re-adding another loop in the kernel with no
preemption point.
Simply taking spinlocks like Stephen did is going to slow down the
other threads, lets face it.
This implementation has a high cost, and provides something that made
no sense in the first place.
next prev parent reply other threads:[~2018-03-01 4:28 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-01 2:01 [PATCH] inet: add bound ports statistic Stephen Hemminger
2018-03-01 2:28 ` Eric Dumazet
2018-03-01 3:32 ` David Miller
2018-03-01 4:28 ` Eric Dumazet [this message]
2018-03-01 16:16 ` Stephen Hemminger
2018-03-01 17:09 ` Eric Dumazet
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