From: "Eads, Gage" <gage.eads@intel.com>
To: David Marchand <david.marchand@redhat.com>,
Steven Lariau <steven.lariau@arm.com>
Cc: Olivier Matz <olivier.matz@6wind.com>, dev <dev@dpdk.org>,
nd <nd@arm.com>
Subject: Re: [dpdk-dev] [PATCH v2 1/5] lib/stack: fix inconsistent weak / strong cas
Date: Mon, 28 Sep 2020 15:58:33 +0000 [thread overview]
Message-ID: <SN6PR11MB257404A8CBF1785BB159AEAFF6350@SN6PR11MB2574.namprd11.prod.outlook.com> (raw)
In-Reply-To: <CAJFAV8wi56h-fBDwDEc-2tJ3B8CTkQh8GmpBadDW4UD7P=-VLg@mail.gmail.com>
> -----Original Message-----
> From: David Marchand <david.marchand@redhat.com>
> Sent: Monday, September 28, 2020 5:23 AM
> To: Steven Lariau <steven.lariau@arm.com>; Eads, Gage <gage.eads@intel.com>
> Cc: Olivier Matz <olivier.matz@6wind.com>; dev <dev@dpdk.org>; nd
> <nd@arm.com>
> Subject: Re: [dpdk-dev] [PATCH v2 1/5] lib/stack: fix inconsistent weak / strong
> cas
>
> On Fri, Sep 25, 2020 at 7:44 PM Steven Lariau <steven.lariau@arm.com> wrote:
> >
> > Fix cmpexchange usage of weak / strong.
> > The generated code is the same on x86 and ARM (there is no weak
> > cmpexchange), but the old usage was inconsistent.
> > For push and pop update size, weak is used because cmpexchange is inside
> > a loop.
> > For pop update root, strong is used even though cmpexchange is inside a
> > loop, because there may be a lot of operations to do in a loop iteration
> > (locate the new head).
>
> Is this patch backport material?
It's not a bugfix. It could help performance on a system with weak
cmpexchange -- e.g. the pop-update change would ensure no spurious
failures (which the code can handle, but would require another relatively
expensive pass through the pop loop.)
Thanks,
Gage
next prev parent reply other threads:[~2020-09-28 15:58 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-11 15:29 [dpdk-dev] [PATCH 0/5] lib/stack: improve lockfree C11 implementation Steven Lariau
2020-09-11 15:29 ` [dpdk-dev] [PATCH 1/5] lib/stack: fix inconsistent weak / strong cas Steven Lariau
2020-09-21 17:16 ` Eads, Gage
2020-09-11 15:29 ` [dpdk-dev] [PATCH 2/5] lib/stack: remove push acquire fence Steven Lariau
2020-09-21 17:16 ` Eads, Gage
2020-09-11 15:29 ` [dpdk-dev] [PATCH 3/5] lib/stack: remove redundant orderings for list->len Steven Lariau
2020-09-21 17:16 ` Eads, Gage
2020-09-11 15:29 ` [dpdk-dev] [PATCH 4/5] lib/stack: reload head when pop fails Steven Lariau
2020-09-21 17:16 ` Eads, Gage
2020-09-11 15:29 ` [dpdk-dev] [PATCH 5/5] lib/stack: remove pop cas release ordering Steven Lariau
2020-09-21 17:17 ` Eads, Gage
2020-09-25 14:27 ` David Marchand
2020-09-25 17:43 ` [dpdk-dev] [PATCH v2 0/5] lib/stack: improve lockfree C11 implementation Steven Lariau
2020-09-25 17:43 ` [dpdk-dev] [PATCH v2 1/5] lib/stack: fix inconsistent weak / strong cas Steven Lariau
2020-09-28 10:22 ` David Marchand
2020-09-28 15:58 ` Eads, Gage [this message]
2020-09-25 17:43 ` [dpdk-dev] [PATCH v2 2/5] lib/stack: remove push acquire fence Steven Lariau
2020-09-25 17:43 ` [dpdk-dev] [PATCH v2 3/5] lib/stack: remove redundant orderings for list->len Steven Lariau
2020-09-25 17:43 ` [dpdk-dev] [PATCH v2 4/5] lib/stack: reload head when pop fails Steven Lariau
2020-09-25 17:43 ` [dpdk-dev] [PATCH v2 5/5] lib/stack: remove pop cas release ordering Steven Lariau
2020-09-25 17:57 ` Eads, Gage
2020-09-30 19:14 ` [dpdk-dev] [PATCH v2 0/5] lib/stack: improve lockfree C11 implementation David Marchand
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