Re: [net-next PATCH 1/3] Revert "icmp: avoid allocating large struct on stack"

On Mon, 2017-01-09 at 09:59 -0800, Cong Wang wrote:

On Mon, Jan 9, 2017 at 9:50 AM, Eric Dumazet [off-list ref] wrote:

quoted

On Mon, 2017-01-09 at 09:42 -0800, Cong Wang wrote:

quoted

On Mon, Jan 9, 2017 at 7:04 AM, Jesper Dangaard Brouer
[off-list ref] wrote:

quoted

This reverts commit 9a99d4a50cb8 ("icmp: avoid allocating large struct
on stack"), because struct icmp_bxm no really a large struct, and
allocating and free of this small 112 bytes hurts performance.

The original commit fixes a warning for large stack usage, icmp_send()
is deep in the call stack.

Your optimization for a slow path makes no sense to me.

Do you have the stack trace of this event ?

Even Linus allowed vmalloc() kernel stacks, while it certainly was an
heresy 10 years ago.

I doubt it makes a difference trying to save 104 bytes of kernel stack.

I think you should have known this, quote from Eric Dumazet
(hopefully the same one):

    On Fri, 2013-05-31 at 22:22 -0700, Eric Dumazet wrote:

    Strange, I posted a patch like that some days ago.

which is from: https://patchwork.ozlabs.org/patch/248051/

Facepalm...

We are in 2017.  Whatever was said in 2013 is irrelevant.

You really should come to netdev conferences so that you understand
goals and efforts, instead of living in your cave.

Then you can slap me in the face, since this is obviously your desire.

Then, we will drink a beer and relax.