Re: Disabling CPUs

On Sat, Oct 8, 2022 at 5:54 PM Kevin Oberman <rkoberman@gmail.com> wrote:

> On Fri, Oct 7, 2022 at 9:56 AM Ian Smith <smithi@nimnet.asn.au> wrote:
>
>> On 7 October 2022 2:05:32 pm AEDT, Kevin Oberman <rkoberman@gmail.com>
>> wrote:
>>
>> [...]
>>
>>  > I've been silent while waiting for the additional memory since I
>>  > could not
>>  > do any real work with only 8G. It finally arrived and I installed it
>>  > yesterday. I'm very happy to say that my VirtualBox VMs seem to now
>>  > be
>>  > working correctly. I've done limited testing, but seen no problems to
>>  > this
>>  > point. Much better than an instant system panic when a VM finished
>>  > loading.
>>  >
>>  > On the plus side, with "cpuset -s 1 -l 0-3", things seem reasonably
>>  > stable.
>>  > That means no crashes with many hours of use and a lot of
>>  > compilations.
>>  > With only 4 cores, it's not a fast as I had hoped, but I will be
>>  > benchmarking soon.
>>
>> Hi Kevin, three questions if I may:
>>
>> I may have missed it, but did you wind up testing sched_ULE vs 4BSD?
>>
>
> cpuset(8) only works with ULE, so that is what I am running. So far I have
> not seen the interactivity issues that caused me to move to 4BSD over a
> decade ago.
>
>
>> Is that 4 cores including HT, or not?
>>
>
> Yes, 2 cores and 4 threads. Sorry to have failed to make that clear. My
> CPU has 2 P cores and 8 E cores. It has never crashed  when running the 2 P
> cores, but I had one crash running the 8 E cores. Now that I have a
> stable system, I may try switching back to just the E cores as they  seem
> to provide almost double the performance of the 2 P cores. Oddly, while
> using rsync to move a big batch of files from my backup disk to the new
> system after cpuset, I saw 0-3 busy, as I would expect, but one E core was
> running at about 30% the entire time, as well. I have no idea why.
>
>>
>> And how much power does your new Thinkpad T16 use on battery, say, at
>> idle and 'fairly busy' (acpiconf -i0) ?
>>
>
> With  the 2 P cores I see about 1.1W idle. Wow! While compiling Firefox
> (all  threads running at over 95%), I see about 25.3W. With a 52500 mWh
> battery, it will last a long time.
> With the 9 E cores I see about 10.4W idle. Wow, the other way. While
> compiling Firefox, I saw a momentary spike of 35W, but it varied between
> 20.5 and 27.8 W with occasional hits up to 31 W. The E core power
> consumption seems far more inconsistent thaa the P cores. compile time with
> P cores was 1:29 while it was only :50 with the 8 E cores.
>
> In both cases I had my Mate desktop running.
>
> The L15 was a piece of junk where I learned my lesson about budget
> systems.  The ABS case started cracking at both hinges after about a year
> of use. That was after about 9 months of trying to get it working properly
> after Lenovo had replaced the motherboard and the disk. and, finally, the
> keyboard. I think the MB was fine, but was the obvious suspect for system
> lock-ups in POST. Took my a while to track it down to the keyboard and the
> tech who swapped it out didn't believe that the keyboard was the problem
> but agreed to humor me. As a result, by the time the case started cracking,
> the warranty had expired. If I had been willing to give up the TrackPoint,
> I would have bought a non-Lenovo/IBM for the first time ever.
>
> The T16 is built like a T series with a metal frame and feels solid. My
> T16 is all SSD. Yes, it's heavier. The L15 flexed noticeably with no frame,
> just the MB, battery, and disk attached to the ABS case.
>
> cheers, Ian
>>
> Sigh. Less than 5 minutes after I sent my reply, the "all E core" system
panicked. The usual vfs/ufs crash in ufs_lookup_ino. I'm back to all P
core" as that has never cashed. So far I have seen no activity on my ticket.
-- 
Kevin Oberman, Part time kid herder and retired Network Engineer
E-mail: rkoberman@gmail.com
PGP Fingerprint: D03FB98AFA78E3B78C1694B318AB39EF1B055683