From: Nathan Bossart <nathandbossart@gmail.com>
To: John Naylor <john.naylor@enterprisedb.com>
Cc: Andres Freund <andres@anarazel.de>
Cc: John Naylor <jcnaylor@gmail.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: optimize lookups in snapshot [sub]xip arrays
Date: Fri, 29 Jul 2022 22:38:11 -0700
Message-ID: <20220730053811.GA417958@nathanxps13> (raw)
In-Reply-To: <CAFBsxsE14aHKR6gr+rEeFJKaBq8sgXctonwpWw3G7twaePHkVA@mail.gmail.com>
References: <20220713170950.GA3116318@nathanxps13>
<20220715200857.nm2gc4weixwlwbnx@awork3.anarazel.de>
<20220717035957.GA3631071@nathanxps13>
<20220725190419.GA4095199@nathanxps13>
<20220726181906.7l4ulzjdblnanclm@alap3.anarazel.de>
<20220728213423.GA408719@nathanxps13>
<CAFBsxsE14aHKR6gr+rEeFJKaBq8sgXctonwpWw3G7twaePHkVA@mail.gmail.com>
On Sat, Jul 30, 2022 at 12:02:02PM +0700, John Naylor wrote:
> On Fri, Jul 29, 2022 at 4:34 AM Nathan Bossart <nathandbossart@gmail.com>
> wrote:
>> * I borrowed USE_SSE2 from one of John Naylor's patches [0]. I'm not
> sure
>> whether this is committable,
>
> I'll be the first to say it's not committable and needs some thought. Since
> there are several recently proposed patches that take advantage of SSE2, it
> seems time for me to open a new thread and get that prerequisite settled.
> I'll do that next week.
Awesome. I will help test and review.
>> so I would welcome thoughts on the proper
>> form. Given the comment says that SSE2 is supported by all x86-64
>> hardware, I'm not seeing why we need the SSE 4.2 checks. Is it not
>> enough to check for __x86_64__ and _M_AMD64?
>
> That's enough for emitting instructions that the target CPU can run, but
> says nothing (I think) about the host compiler's ability to understand the
> intrinsics and associated headers. The architecture is old enough that
> maybe zero compilers in the buildfarm that target AMD64 fail to understand
> SSE2 intrinsics, but I hadn't looked into it. The SSE 4.2 intrinsics check
> is not necessary, but it was sufficient and already present, so I borrowed
> it for the PoC.
Got it, makes sense.
--
Nathan Bossart
Amazon Web Services: https://aws.amazon.com
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To: pgsql-hackers@postgresql.org
Cc: nathandbossart@gmail.com, john.naylor@enterprisedb.com, andres@anarazel.de, jcnaylor@gmail.com
Subject: Re: optimize lookups in snapshot [sub]xip arrays
In-Reply-To: <20220730053811.GA417958@nathanxps13>
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