Re: [PATCH 1/2] bswap.h: drop unaligned loads
- From
Thomas Guyot <tguyot@gmail.com>
- Date
- Sep 25, 2020, 20:48 UTC
- Message-ID
- <6d48c9ee-d8cc-1f22-80bb-f249c94f9767@gmail.com>
- In-Reply-To
- <CAPUEspjpUeaqCCuBJpQLSTv=C_P4f5h22HoTPm9+9rB7k0NkaQ@mail.gmail.com>
On 2020-09-25 05:05, Carlo Arenas wrote:
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> On Thu, Sep 24, 2020 at 6:15 PM brian m. carlson > <sandals@crustytoothpaste.net> wrote: >> On 2020-09-24 at 19:21:11, Jeff King wrote: >>> [stock] >>> Benchmark #1: t/helper/test-tool sha1 <foo.rand >>> Time (mean ± σ): 6.638 s ± 0.081 s [User: 6.269 s, System: 0.368 s] >>> Range (min … max): 6.550 s … 6.841 s 10 runs > > slightly offtopic but what generates this nicely formatted output?
It turns out I may have finally reproduced my diff speed regression at home - just today - and I read this :) I may use it to test, nice timing!
About my unrelated regression, TL;DR, have anyone benchmarked under a VM? (more context below...)
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>> I cannot speak for s390, since I have never owned one > > I happen to be lucky enough to have access to one (RHEL 8.2/z15, gcc > 8.3.1) and seems (third consecutive run): > > stock: user: 7.555s, system: 1.191s > -DNO_UNALIGNED_LOADS: user: 7.561s, system: 1.189s
So also somewhat offtopic too, but I've been trying lately to reproduce a speed regression with "git diff --no-ext-diff --quiet" (used by git prompt in contrib) on some large repos between 2.9.5 and 2.16.2. Overall the diff was over 3x as slow where I tested, and I measured a couple timings between mmap of the same two large files between the two version, the delta was approx 10x! (no other syscalls so it's all computing and - if my theory proves right - I guess a lot of pagefaults or similar handling control back to the host).
I prepped a VM where I will do more testing (I ran one preliminary test and there seemed to be a visible difference, but I didn't have a proper repo to test with yet). The point being it might be worth comparing the two on VM's as well.
Regards,
Thomas