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Re: asymmetric smp
On 2014-04-01 23:04, Warner Losh wrote:
On Apr 1, 2014, at 5:49 AM, Johnny Billquist <bqt%softjar.se@localhost> wrote:
Is this the right time to ask why booting NetBSD on a VAX (a 3500) now takes
more than 15 minutes? What is the system doing all that time???
FreeBSD used to take forever to boot on certain low-end ARM CPUs with /etc/rc.d
after it was imported from NetBSD. This was due to crappy root-device
performance (100kB/s is enough for anybody, right?) and crappy, at the time,
pmap code that caused excess page traffic in the /etc/rc.d environment. Perhaps
those areas would be fruitful to profile? Also, there were some inefficiencies
that were either the result of a botched port, or were basic to the system that
got fixed. Between fixing all these things, the boot time went from 10 minutes
down to ~20s.
Always nice with some ideas. The problem here is that this used to be
way faster in the past, but have slowed down recently.
The time between entering a username and getting the password prompt in
the same 3500 with the latest release is something like 30 seconds.
This is on an otherwise idle system, where boot has completed. 30
seconds (approximately, I should time it) just from pressing enter after
the username, until I just get the "Password:" prompt seems incredible
The root fs in on nfs, as I'm running the machine diskless. Disk is
served from a -current NetBSD/alpha system sitting right next to it. And
I have changed the Alpha to run at 10 MB/s half duplex, and I have 2k
block size for NFS. Login is obviously already running, since that is
what also prompts for the username, and doing it twice should even put
some stuff in local cache.
The 3500 have 16 megs of memory, and looking at the system once logged
in, I'm not using much CPU, nor is all memory committed yet.
I have (on and off) complained about perceived slowing down of
NetBSD/vax over the years, but it's been a little while since I last
tried, and my experience now on the 3500 is so horrible that I'd say it
is very close to impossible to run NetBSD on it anymore.
And actually, the Alpha is pretty saggy with -current as well. No idea
why, but occasionally it spends a whole lot of time in system mode.
Might be related. Or not...
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