From: Andrea Parri <parri.andrea@gmail.com>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Jonas Oberhauser <jonas.oberhauser@huaweicloud.com>,
paulmck@kernel.org, will@kernel.org, peterz@infradead.org,
boqun.feng@gmail.com, npiggin@gmail.com, dhowells@redhat.com,
j.alglave@ucl.ac.uk, luc.maranget@inria.fr, akiyks@gmail.com,
dlustig@nvidia.com, joel@joelfernandes.org, urezki@gmail.com,
quic_neeraju@quicinc.com, frederic@kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] tools/memory-model: Make ppo a subrelation of po
Date: Wed, 18 Jan 2023 21:22:35 +0100 [thread overview]
Message-ID: <Y8hS5iq2+vbcYlkT@andrea> (raw)
In-Reply-To: <Y8hN7vs/w8LhMasT@rowland.harvard.edu>
> It would be nice here to have a separate term for a potentially
> cross-CPU fence.
>
> In fact, why don't we make a concerted effort to straighten out the
> terminology more fully? Now seems like a good time to do it.
>
> To begin with, let's be more careful about the difference between an
> order-inducing object (an event or pair of events) and the relation of
> being ordered by such an object. For instance, given:
>
> A: WRITE_ONCE(x, 1);
> B: smp_mb();
> C: r1 = READ_ONCE(y);
>
> then B is an order-inducing object (a memory barrier), and (A,C) is a
> pair of events ordered by that object. In general, an order is related
> to an order-inducing object by:
>
> order = po ; [order-inducing object] ; po
>
> with suitable modifications for things like smp_store_release where
> one of the events being ordered _is_ the order-inducing event.
>
> So for example, we could consistently refer to all order-inducing events
> as either barriers or fences, and all order-reflecting relations as
> orders. This would require widespread changes to the .cat file, but I
> think it would be worthwhile.
>
> (Treating "barrier" and "fence" as synonyms seems to be too deeply
> entrenched to try and fight against.)
>
> Once that is straightened out, we can distinguish between fences or
> orders that are weak vs. strong. And then we can divide up strong
> fences/orders into single-CPU vs. cross-CPU, if we want to.
>
> How does that sound?
Sounds like a lot of work, renaming and review, for no clear win
to me. :-) But hey, if other are into it...
Andrea
next prev parent reply other threads:[~2023-01-18 20:22 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-17 19:31 [PATCH] tools/memory-model: Make ppo a subrelation of po Jonas Oberhauser
2023-01-17 23:45 ` Boqun Feng
2023-01-18 12:13 ` Jonas Oberhauser
2023-01-18 19:52 ` Alan Stern
2023-01-18 20:22 ` Andrea Parri [this message]
2023-01-18 21:38 ` Jonas Oberhauser
2023-01-19 3:13 ` Alan Stern
2023-01-19 15:05 ` Jonas Oberhauser
2023-01-19 20:06 ` Alan Stern
2023-01-20 11:12 ` Jonas Oberhauser
2023-01-20 16:32 ` Alan Stern
2023-01-21 0:41 ` Jonas Oberhauser
2023-01-21 20:56 ` Alan Stern
2023-01-23 13:59 ` Jonas Oberhauser
2023-01-23 17:28 ` Alan Stern
2023-01-23 19:33 ` Jonas Oberhauser
2023-01-23 21:10 ` Alan Stern
2023-01-24 13:14 ` Jonas Oberhauser
2023-01-24 17:14 ` Alan Stern
2023-01-24 20:23 ` Jonas Oberhauser
2023-01-25 2:57 ` Alan Stern
2023-01-25 13:06 ` Jonas Oberhauser
2023-01-25 15:56 ` Alan Stern
2023-01-23 18:25 ` Jonas Oberhauser
2023-01-23 20:25 ` Alan Stern
2023-01-24 12:54 ` Jonas Oberhauser
2023-01-24 16:03 ` Alan Stern
2023-01-18 21:30 ` Andrea Parri
2023-01-18 22:02 ` Jonas Oberhauser
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=Y8hS5iq2+vbcYlkT@andrea \
--to=parri.andrea@gmail.com \
--cc=akiyks@gmail.com \
--cc=boqun.feng@gmail.com \
--cc=dhowells@redhat.com \
--cc=dlustig@nvidia.com \
--cc=frederic@kernel.org \
--cc=j.alglave@ucl.ac.uk \
--cc=joel@joelfernandes.org \
--cc=jonas.oberhauser@huaweicloud.com \
--cc=linux-kernel@vger.kernel.org \
--cc=luc.maranget@inria.fr \
--cc=npiggin@gmail.com \
--cc=paulmck@kernel.org \
--cc=peterz@infradead.org \
--cc=quic_neeraju@quicinc.com \
--cc=stern@rowland.harvard.edu \
--cc=urezki@gmail.com \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).