From: Jan Beulich <jbeulich@suse.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: "Roger Pau Monné" <roger.pau@citrix.com>, "Wei Liu" <wl@xen.org>,
Xen-devel <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH] xen: Fold exit paths in find_text_region()
Date: Mon, 17 Apr 2023 11:00:41 +0200 [thread overview]
Message-ID: <dfc9f77c-ab6e-a4cb-7fcf-4fa1d8371902@suse.com> (raw)
In-Reply-To: <20230413192201.3255984-1-andrew.cooper3@citrix.com>
On 13.04.2023 21:22, Andrew Cooper wrote:
> Despite rcu_read_unlock() being fully inlineable, the optimiser cannot fold
> these exit paths, because of the various compiler barriers providing RCU
> safety. Help the compiler out.
Mind me asking about "cannot"? Iirc the compiler is permitted to fold
even volatile asm()s, as long as certain guarantees aren't violated.
With "... often won't ..." or alike I'd be happy to give my ack, albeit
doing so with another maintainer's questions pending (and imo wrongly
taken by you as possibly insulting) it's never really clear to me
whether doing so is appropriate. I would specifically argue that ...
> This compiles to marginally better code in all cases. No functional change.
... even minor improvements are worth it.
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Preferably (unless proven wrong) with said adjustment and on the basis
that Julien signals his question as addressed (once it really is, of
course):
Acked-by: Jan Beulich <jbeulich@suse.com>
Jan
prev parent reply other threads:[~2023-04-17 9:01 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-13 19:22 [PATCH] xen: Fold exit paths in find_text_region() Andrew Cooper
2023-04-13 20:13 ` Julien Grall
2023-04-13 22:09 ` Andrew Cooper
2023-04-13 23:01 ` Stefano Stabellini
2023-04-17 9:00 ` Jan Beulich [this message]
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