From: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>
To: "Richardson, Bruce" <bruce.richardson@intel.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH 2/2] eal/x86: Use lock-prefixed instructions to reduce cost of rte_smp_mb()
Date: Mon, 11 Dec 2017 17:30:08 +0000 [thread overview]
Message-ID: <2601191342CEEE43887BDE71AB9772585FAC8193@irsmsx105.ger.corp.intel.com> (raw)
In-Reply-To: <20171211171121.GB2232@bricha3-MOBL3.ger.corp.intel.com>
Hi Bruce,
> -----Original Message-----
> From: Richardson, Bruce
> Sent: Monday, December 11, 2017 5:11 PM
> To: Ananyev, Konstantin <konstantin.ananyev@intel.com>
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH 2/2] eal/x86: Use lock-prefixed instructions to reduce cost of rte_smp_mb()
>
> On Fri, Dec 01, 2017 at 11:12:51AM +0000, Konstantin Ananyev wrote:
> > On x86 it is possible to use lock-prefixed instructions to get
> > the similar effect as mfence.
> > As pointed by Java guys, on most modern HW that gives a better
> > performance than using mfence:
> > https://shipilev.net/blog/2014/on-the-fence-with-dependencies/
> > That patch adopts that technique for rte_smp_mb() implementation.
> > On BDW 2.2 mb_autotest on single lcore reports 2X cycle reduction,
> > i.e. from ~110 to ~55 cycles per operation.
> >
> > Signed-off-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
> > ---
> > .../common/include/arch/x86/rte_atomic.h | 45 +++++++++++++++++++++-
> > 1 file changed, 43 insertions(+), 2 deletions(-)
> >
> <snip>
> > + * As pointed by Java guys, that makes possible to use lock-prefixed
> > + * instructions to get the same effect as mfence and on most modern HW
> > + * that gives a better perfomarnce than using mfence:
> > + * https://shipilev.net/blog/2014/on-the-fence-with-dependencies/
> > + * So below we use that technique for rte_smp_mb() implementation.
> > + */
> > +
> > +#ifdef RTE_ARCH_I686
> > +#define RTE_SP RTE_STR(esp)
> > +#else
> > +#define RTE_SP RTE_STR(rsp)
> > +#endif
> > +
> > +#define RTE_MB_DUMMY_MEMP "-128(%%" RTE_SP ")"
> > +
> > +static __rte_always_inline void
> > +rte_smp_mb(void)
> > +{
> > + asm volatile("lock addl $0," RTE_MB_DUMMY_MEMP "; " ::: "memory");
> > +}
>
> Rather than #defining RTE_SP and RTE_MB_DUMMY_MEMP, why not just put the
> #ifdef into the rte_smp_mb itself and have two asm volatile lines with
> hard-coded register names in them? It would be shorter and I think a lot
> easier to read.
Fine by me.
Any other thoughts from anyone till I submit v2?
Konstantin
next prev parent reply other threads:[~2017-12-11 17:30 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-01 11:12 [dpdk-dev] [PATCH 1/2] test/test: introduce new test-case for rte_smp_mb() Konstantin Ananyev
2017-12-01 11:12 ` [dpdk-dev] [PATCH 2/2] eal/x86: Use lock-prefixed instructions to reduce cost of rte_smp_mb() Konstantin Ananyev
2017-12-01 18:04 ` Stephen Hemminger
2017-12-01 23:08 ` Ananyev, Konstantin
2018-03-08 21:15 ` Stephen Hemminger
2017-12-11 17:11 ` Bruce Richardson
2017-12-11 17:30 ` Ananyev, Konstantin [this message]
2017-12-18 15:34 ` [dpdk-dev] [PATCH v2 0/2] eal/x86: Optimize rte_smp_mb() and create a new test case for it Konstantin Ananyev
2017-12-18 15:34 ` [dpdk-dev] [PATCH v2 1/2] test/test: introduce new test-case for rte_smp_mb() Konstantin Ananyev
2018-01-12 17:23 ` Thomas Monjalon
2018-01-12 17:58 ` Ananyev, Konstantin
2018-01-13 13:54 ` Wiles, Keith
2018-01-13 13:54 ` Wiles, Keith
2018-01-15 15:04 ` [dpdk-dev] [PATCH v3 0/2] eal/x86: Optimize rte_smp_mb() and create a new test case for it Konstantin Ananyev
2018-01-15 15:04 ` [dpdk-dev] [PATCH v3 1/2] test/test: introduce new test-case for rte_smp_mb() Konstantin Ananyev
2018-01-16 0:16 ` Thomas Monjalon
2018-01-15 15:04 ` [dpdk-dev] [PATCH v3 2/2] eal/x86: Use lock-prefixed instructions to reduce cost of rte_smp_mb() Konstantin Ananyev
2018-01-15 15:09 ` Konstantin Ananyev
[not found] ` <8b05f533-d146-7f97-48f4-82ddcfc3613b@redhat.com>
2018-01-16 1:54 ` [dpdk-dev] Fwd: " Michael S. Tsirkin
2018-01-29 9:29 ` Ananyev, Konstantin
2018-01-29 17:29 ` Michael S. Tsirkin
2018-01-29 15:47 ` [dpdk-dev] " Thomas Monjalon
2018-01-30 19:33 ` Stephen Hemminger
2017-12-18 15:34 ` [dpdk-dev] [PATCH v2 " Konstantin Ananyev
2017-12-18 15:46 ` Bruce Richardson
2017-12-11 17:08 ` [dpdk-dev] [PATCH 1/2] test/test: introduce new test-case for rte_smp_mb() Bruce Richardson
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=2601191342CEEE43887BDE71AB9772585FAC8193@irsmsx105.ger.corp.intel.com \
--to=konstantin.ananyev@intel.com \
--cc=bruce.richardson@intel.com \
--cc=dev@dpdk.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).