Re: very slow ssh / sshd performance on current

[Alexander Bluhm]

On Fri, Sep 02, 2016 at 09:43:13AM +0200, Andreas Bartelt wrote:
> I'm observing very slow ssh / sshd performance on current (tested on amd64).
> Throughput is less than 1/50th of what I'm typically seeing on my boxes.
> This drop in performance seems to be independent of the used ciphers (tested
> with aes-gcm-128 & chacha20-poly1305).
> 
> All tested interfaces are em(4) which, however, seems to be completely
> unrelated since I don't observe this huge drop in performance via nc(1) -
> it's >70 MB/s via nc(1) vs. ~1-2 MB/s via ssh/scp.

I see a performance drop to 10 Mbit/sec on some old i386 machines
with em(4).  Can you try this kernel diff to see wether it is the
same problem?

bluhm

Index: kern/uipc_socket.c
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/sys/kern/uipc_socket.c,v
retrieving revision 1.155
diff -u -p -r1.155 uipc_socket.c
--- kern/uipc_socket.c  25 Aug 2016 14:13:19 -0000      1.155
+++ kern/uipc_socket.c  29 Aug 2016 18:02:24 -0000
@@ -544,7 +544,7 @@ m_getuio(struct mbuf **mp, int atomic, l
 
                resid = ulmin(resid, space);
                if (resid >= MINCLSIZE) {
-                       MCLGETI(m, M_NOWAIT, NULL, ulmin(resid, MAXMCLBYTES));
+                       MCLGETI(m, M_NOWAIT, NULL, ulmin(resid, PAGE_SIZE));
                        if ((m->m_flags & M_EXT) == 0)
                                goto nopages;
                        mlen = m->m_ext.ext_size;