David Miller
2017-Mar-19 01:21 UTC
[Bridge] [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to refcount_t
From: Herbert Xu <herbert at gondor.apana.org.au> Date: Sun, 19 Mar 2017 00:47:59 +0800> Eric Dumazet <eric.dumazet at gmail.com> wrote: >> On Fri, 2017-03-17 at 07:42 +0000, Reshetova, Elena wrote: >> >>> Should we then first measure the actual numbers to understand what we >>> are talking here about? >>> I would be glad to do it if you suggest what is the correct way to do >>> measurements here to actually reflect the real life use cases. >> >> How have these patches been tested in real life exactly ? >> >> Can you quantify number of added cycles per TCP packet, where I expect >> we have maybe 20 atomic operations in all layers ... > > I completely agree. I think this thing needs to default to the > existing atomic_t behaviour.I totally agree as well, the refcount_t facility as-is is unacceptable for networking.
Peter Zijlstra
2017-Mar-20 10:39 UTC
[Bridge] [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to refcount_t
On Sat, Mar 18, 2017 at 06:21:21PM -0700, David Miller wrote:> From: Herbert Xu <herbert at gondor.apana.org.au> > Date: Sun, 19 Mar 2017 00:47:59 +0800 > > > Eric Dumazet <eric.dumazet at gmail.com> wrote: > >> On Fri, 2017-03-17 at 07:42 +0000, Reshetova, Elena wrote: > >> > >>> Should we then first measure the actual numbers to understand what we > >>> are talking here about? > >>> I would be glad to do it if you suggest what is the correct way to do > >>> measurements here to actually reflect the real life use cases. > >> > >> How have these patches been tested in real life exactly ? > >> > >> Can you quantify number of added cycles per TCP packet, where I expect > >> we have maybe 20 atomic operations in all layers ... > > > > I completely agree. I think this thing needs to default to the > > existing atomic_t behaviour. > > I totally agree as well, the refcount_t facility as-is is unacceptable > for networking.Can we at least give a benchmark and have someone run numbers? We should be able to quantify these things.
Herbert Xu
2017-Mar-20 13:16 UTC
[Bridge] [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to refcount_t
On Mon, Mar 20, 2017 at 11:39:37AM +0100, Peter Zijlstra wrote:> > Can we at least give a benchmark and have someone run numbers? We should > be able to quantify these things.Do you realise how many times this thing gets hit at 10Gb/s or higher? Anyway, since you're proposing this change you should demonstrate that it does not cause a performance regression. Cheers, -- Email: Herbert Xu <herbert at gondor.apana.org.au> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt