Displaying 4 results from an estimated 4 matches for "hs21xm".
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h21xm
2020 Jun 14
4
very low performance of Xen guests
Hello
??? For the past months I've been testing upgrading my Xen hosts to
CentOS 7 and I face an issue for which I need your help to solve.
??? The testing machines are IBM blades, model H21 and H21XM. Initial
tests were performed on the H21 with 16 GB RAM; during the last 6=7
weeks I've been using the H21XM with 64 GB. In all cases the guests were
fully updated CentOS 7 --
2020 Jun 18
0
very low performance of Xen guests
...>
>
> If you can do a full reinstall, could you see if a KVM host/guest
> combo has the same problem? That would at least point the finger more
> firmly at VT, spectre or something else.
>
>
I finally managed to install a fresh KVM host / guest pair on an
identical blade ( HS21XM, 64 GB ram, 2*E5450@ 3.00GHz ). Here are the
results I see:
1. KVM host, stock instalation and fully updated, kernel 3.10.0-1127.10.1
#cd /sys/kernel/debug/x86/
#cat ibrs_enabled pti_enabled retp_enabled
0
1
1
#time yum -y reinstall kernel-3.10.0-1127.el7.x86_64
real??? 0m50.026s
user??? 0m32.8...
2020 Jun 15
0
very low performance of Xen guests
..., changing the elevator had no influence
> either.
>
> Here is the info which I think that should be relevant for the
> software versions in use. Feel free to ask for any additional info.
>
Is there a way to boot up a PV guest versus an HVM? I could not find a
H21XM but found an HS21XM on the iBM site and that seemed to be a 4 core 8
thread cpu which looks 'old' enough that the Spectre/etc fixes to improve
performance after the initial hit were not done. (Basically I was told that
if the CPU was older than 2012, just turn off hyperthreading altogether to
try and get back...
2020 Jun 15
1
very low performance of Xen guests
...s there a way to boot up a PV guest versus an HVM?
If I understood the docs correctly, newer xen does only PVHVM (
xen_platform_pci=1 activates that ) and HVM. But they say it's better
than PV. And I did verify, PVHVM is indeed enabled and active
> I could not find a H21XM but found an HS21XM on the iBM
My bad. The blades are indeed HS21 (Type 8853) and HS21 XM (Type 7995).
The XM blades have 2*Xeon E5450 at 3GHz / 12GB L1 cache processors. The
options I can fiddle with are https://imgur.com/a/DonXe5P
AFAICS the setttings are reasonable but please do let me know if there
is anythin...