| From: | Nathan Bossart <nathandbossart(at)gmail(dot)com> |
|---|---|
| To: | Salvatore Dipietro <dipietro(dot)salvatore(at)gmail(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Robert Haas <robertmhaas(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org, Salvatore Dipietro <dipiets(at)amazon(dot)com>, blakgeof(at)amazon(dot)com |
| Subject: | Re: Remove Instruction Synchronization Barrier in spin_delay() for ARM64 architecture |
| Date: | 2025-08-11 19:58:38 |
| Message-ID: | aJpLbvj48tMXmkQ6@nathan |
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| Lists: | pgsql-hackers |
On Thu, Jun 19, 2025 at 12:10:52PM -0700, Salvatore Dipietro wrote:
> We can notice that with low concurrency (1,2,4) results are similar
> while with medium concurrency (8,16)
> the No-ISB approach can introduce some regression especially on
> smaller instances. However, we can see some significant
> positive performance impact with high concurrency (>=32) settings on
> large instances (up to 8.76x on m7g.16xl with 256 concurrency).
Given these mixed results, it's unclear to me how exactly we should
proceed. Perhaps there is another approach that reduces the regressions to
a negligible level while still producing gains at higher levels of
concurrency. Or maybe we can convince ourselves that these regressions
aren't worth worrying about, but that seems like a bit of a stretch to me.
--
nathan
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