From: Heiko Carstens <hca@linux.ibm.com>
To: Alexander Gordeev <agordeev@linux.ibm.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
borntraeger@de.ibm.com, frankja@linux.ibm.com, nrb@linux.ibm.com,
nsg@linux.ibm.com, svens@linux.ibm.com, gor@linux.ibm.com,
gerald.schaefer@linux.ibm.com
Subject: Re: [PATCH v1 1/1] s390: mm: convert pgste locking functions to C
Date: Wed, 6 Dec 2023 10:15:41 +0100 [thread overview]
Message-ID: <20231206091541.6897-A-hca@linux.ibm.com> (raw)
In-Reply-To: <ZXA4XkU0M1BZ5R5k@li-008a6a4c-3549-11b2-a85c-c5cc2836eea2.ibm.com>
On Wed, Dec 06, 2023 at 10:01:18AM +0100, Alexander Gordeev wrote:
> On Tue, Dec 05, 2023 at 06:32:52PM +0100, Claudio Imbrenda wrote:
> ...
> > + do {
> > + value = __atomic64_or_barrier(PGSTE_PCL_BIT, ptr);
>
> Would it make sense to cpu_relax() here, e.g with a follow-up patch?
No, because cpu_relax() is a no-op on our architecture (besides that it
translates to barrier(); but __atomic64_or_barrier() obviously comes also
with barrier() semantics).
We used to do diag 0x44 with cpu_relax() but that caused many performance
problems, therefore we removed diag 0x44 completely from the kernel quite
some time ago.
See also commit 1b68ac8678a8 ("s390: remove last diag 0x44 caller").
next prev parent reply other threads:[~2023-12-06 9:15 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-05 17:32 [PATCH v1 1/1] s390: mm: convert pgste locking functions to C Claudio Imbrenda
2023-12-05 18:49 ` Heiko Carstens
2023-12-06 8:58 ` Alexander Gordeev
2023-12-06 9:01 ` Alexander Gordeev
2023-12-06 9:15 ` Heiko Carstens [this message]
2023-12-06 13:14 ` Alexander Gordeev
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