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Re: Increased execution time with TCI in latest git master (was: Re: [PU

From: Stefan Weil
Subject: Re: Increased execution time with TCI in latest git master (was: Re: [PULL 00/46] tcg patch queue)
Date: Sun, 7 Feb 2021 23:00:57 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.0

On 07.02.21 19:37, Richard Henderson wrote:
> On 2/7/21 2:50 AM, Stefan Weil wrote:
>> Your latest code from the rth7680/tci-next branch is twice as fast as my code
>> with BIOS boot and qemu-x86_64 on sparc64. That's great.
>> With that code I don't get any BIOS output at all when running qemu-i386.
>> That's not so good.
>> Did I test the correct branch? If yes, I could try the same test on amd64 and
>> arm64 hosts.
> Yes, tci-next is the correct branch.  I've just rebased it against master,
> which includes the first 30-odd patches.
> What host do you not see bios output from qemu-system-i386 (I assume that's a
> typo above)?  I see correct output on x86_64, sparc64, ppc64le, and aarch64 
> hosts.

Right, the TCI test was done with qemu-system-i386 of course.

I repeated the TCI test with qemu-system-i386 and qemu-system-x86_64 and
the rebased branch.

The system emulation for a BIOS boot works on Apple M1 arm64 with less
that 5 s user time (similar fast as before the latest TCI changes):

./qemu-system-i386 --nographic
  4,28s user 0,03s system 37% cpu 11,398 total
./qemu-system-x86_64 --nographic
  4,39s user 0,03s system 34% cpu 12,982 total

The same test shows similar timings on an AMD64 server:

./qemu-system-i386 --nographic
 user 0m4,958s before tcg-next, 0m5,115s after tcg-next

./qemu-system-x86_64 --nographic
 user 0m4,967s before tcg-next, 0m5,263s after tcg-next

Here tci-next is slightly slower than the old code.

The results on sparc64 did not change with the rebased tci-next:
qemu-system-i386 still fails to run, and qemu-system-x86_64 takes about
20 s user time.


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