[Vm-dev] Why Aren’t More Users More Happy With Our VMs?
pbpublist at gmail.com
Thu Sep 20 14:57:39 UTC 2018
That's excellent to know... I wasn't aware that this was being looked at.
Something that's been in the back of my mind for a while is trying to
measure JIT performance vs. JIT code cache size, architecture being run on,
and workload. As I understand it, the JIT code cache is a fixed size
(~1meg iirc) which doesn't make a lot of sense to me given the variance in
CPU cache size (generally in the range of 512k-4m depending on whether
you're running on Intel/AMD/ARM, desktop/server, low/high end, HT
enabled/disabled, and oddball/extreme CPU configurations like the Intel
5775C with it's 128meg LLC) and then there's the cost of potentially
thrashing the JIT cache vs maintaining a larger cache despite the fact that
it might exceed the capacity of the CPU cache. (However to measure this I
think a few new VM params would be needed: a r/w JIT cache size, JIT cache
code evictions (since last full gc?), JIT cache code additions (since last
full gc?), Avg cache code size... the current machine code
method/compaction counts are a good start but a bit coarse). Just thought
I'd throw this out there since it seemed apropos...
On Thu, Sep 20, 2018, 5:02 AM Tobias Pape <Das.Linux at gmx.de> wrote:
> Hi Todd,
> > On 20.09.2018, at 10:28, Todd Blanchard <tblanchard at mac.com> wrote:
> > I'm curious if anyone has seen this writeup on VM performance
> > I found the article very insightful and was curious how we stacked up.
> > Have written the author to ask about including us in future research.
> > Cheers.
> > -Todd Blanchard
> I know the author and share similar concerns.
> In fact, for stuff we do here with RSqueak/VM and GraalSqueak, we pay
> attention to at least some of the concerns Laurie mentions.
> Have a look at SMark, which tries to give a reasonable benchmark set set.
> also, there's our benchmark runner that builds on SMark
> We also have a codespeed up here: http://speed.squeak.org/
> Yea that does not all address the authors issues, but we try :D
> Best regards
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