Re: [Linux-decnet-user] LAT for linux using DECserver 90L+ and VT420

[John F. <jo...@fo...>]

On Tue, 30 Sep 2008, John Forkosh wrote:
> On Tue, 30 Sep 2008, Christine Caulfield wrote:
> [...]
>> The next thing to do would be to strace the latd daemon
>> (Warning, this generates a lot of output!) with timestamps
>> (strace -tt -p <pid>) to see just at which point the
>> keystroke is being delayed.
>> 
> Okay, I'll do that while entering keystrokes on the VT420,
> and then try to grep -v the  strace 2>output  to remove
> any unnecessary heartbeat-type stuff. If the strace output
> seems overly long, I'll put it on my website and post
> a link to the mailing list.

Full output is at http://www.forkosh.com/strace.txt

Here's what it represents:
   I typed ........ on the VT until a dot didn't echo.
Then I typed a / (after which ./ immediately echoed),
followed by more ...'s until the next dot didn't echo.
So you'll see .........../............/.....etc.
Each / means the dot before it didn't echo immediately.
And there are lots of timestamps in between.
I've reproduced a few snippets below, but don't know
if they're useful ones.

As mentioned previously, please enjoy your vacation,
and get around to this whenever you feel like it.
I'm in no rush and under no pressure whatsoever.
Thanks again,
John

A typical "dot snippet" is
----------------------------------------------------------------
19:24:58.846386 select(1024, [4 5 6], NULL, NULL, {0, 80000}) = 1
    (in [4], left{0, 80000})
19:24:58.846915 recvmsg(4, {msg_name(18)={sa_family=AF_PACKET,
    proto=0x6004, if2, pkttype=PACKET_HOST, addr(6)={1, 08002b337f19},
    msg_iov(1)=[{"\2\1\1\0\1\366n~
    \1\6\1\0.\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 1600}],
    msg_controllen=0, msg_flags=0}, 0) = 46
19:24:58.847324 write(7, ".", 1)        = 1
19:24:58.847656 ioctl(7, FIONREAD, [1]) = 0
19:24:58.847902 select(1024, [4 5 6], NULL, NULL, {0, 80000}) = 0
    (Timeout)
etc.

And here's a "dot snippet" that didn't echo (because the next
char I typed is a /)
----------------------------------------------------------------
19:24:58.846386 select(1024, [4 5 6], NULL, NULL, {0, 80000}) = 1
    (in [4], left{0, 80000})
19:24:58.846915 recvmsg(4, {msg_name(18)={sa_family=AF_PACKET,
    proto=0x6004, if2, pkttype=PACKET_HOST, addr(6)={1, 08002b337f19},
    msg_iov(1)=[{"\2\1\1\0\1\366n~
    \1\6\1\0.\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 1600}],
    msg_controllen=0, msg_flags=0}, 0) = 46
19:24:58.847324 write(7, ".", 1)        = 1
19:24:58.847656 ioctl(7, FIONREAD, [1]) = 0
19:24:58.847902 select(1024, [4 5 6], NULL, NULL, {0, 80000}) = 0
    (Timeout)
19:24:58.925342 read(7, ".", 126)       = 1
19:24:58.925610 sendto(4,
    "\0\1\1\366\1\0\177n\6\1\0\17\240\10\7\10osh@psi2star:
    ~"..., 46, 0, {sa_family=AF_PACKET, proto=0x6004, if2,
    pkttype=PACKET_MULTICAST,
    addr(6)={0, 08002b337f19}, 20) = 46
19:24:58.925975 gettimeofday({1222817098, 926074}, NULL) = 0
19:24:58.926194 time(NULL)              = 1222817098
19:24:58.926384 time(NULL)              = 1222817098
19:24:58.926588 select(1024, [4 5 6], NULL, NULL, {0, 80000}) = 0
    (Timeout)