DPDK patches and discussions
 help / color / mirror / Atom feed
From: Ruifeng Wang <Ruifeng.Wang@arm.com>
To: Omkar Maslekar <omkar.maslekar@intel.com>, "dev@dpdk.org" <dev@dpdk.org>
Cc: "bruce.richardson@intel.com" <bruce.richardson@intel.com>,
	"ciara.loftus@intel.com" <ciara.loftus@intel.com>,
	"drc@linux.vnet.ibm.com" <drc@linux.vnet.ibm.com>,
	"jerinj@marvell.com" <jerinj@marvell.com>,
	Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>,
	nd <nd@arm.com>
Subject: Re: [dpdk-dev] [PATCH v6] eal: add cache-line demote support
Date: Tue, 13 Oct 2020 02:59:24 +0000
Message-ID: <HE1PR0802MB234538D6A7FD6A76586EC8849E040@HE1PR0802MB2345.eurprd08.prod.outlook.com> (raw)
In-Reply-To: <1602497980-20680-2-git-send-email-omkar.maslekar@intel.com>


> -----Original Message-----
> From: Omkar Maslekar <omkar.maslekar@intel.com>
> Sent: Monday, October 12, 2020 6:20 PM
> To: dev@dpdk.org
> Cc: bruce.richardson@intel.com; ciara.loftus@intel.com;
> omkar.maslekar@intel.com; drc@linux.vnet.ibm.com; jerinj@marvell.com;
> Ruifeng Wang <Ruifeng.Wang@arm.com>; Honnappa Nagarahalli
> <Honnappa.Nagarahalli@arm.com>
> Subject: [PATCH v6] eal: add cache-line demote support
> 
> rte_cldemote is similar to a prefetch hint - in reverse. cldemote(addr)
> enables software to hint to hardware that line is likely to be shared.
> Useful in core-to-core communications where cache-line is likely to be
> shared. ARM and PPC implementation is provided with NOP and can be
> added if any equivalent instructions could be used for implementation on
> those architectures.
> 
> Signed-off-by: Omkar Maslekar <omkar.maslekar@intel.com>
> Acked-by: Bruce Richardson <bruce.richardson@intel.com>
> 
> ---
> v6: marked rte_cldemote as experimental
>     added rte_cldemote call in existing app/test_prefetch.c
> 
> v5: documentation updated
>     fixed formatting issue in release notes
>     added Acked-by: Bruce Richardson <bruce.richardson@intel.com>
> *
> v4: updated bold text for title and fixed margin in release notes
> *
> v3: fixed warning regarding whitespace
> *
> v2: documentation updated
> ---
> ---
>  app/test/test_prefetch.c                      |  4 ++++
>  doc/guides/rel_notes/release_20_11.rst        |  7 +++++++
>  lib/librte_eal/arm/include/rte_prefetch_32.h  |  8 ++++++++
> lib/librte_eal/arm/include/rte_prefetch_64.h  |  8 ++++++++
> lib/librte_eal/include/generic/rte_prefetch.h | 16 ++++++++++++++++
>  lib/librte_eal/ppc/include/rte_prefetch.h     |  8 ++++++++
>  lib/librte_eal/x86/include/rte_prefetch.h     | 12 ++++++++++++
>  7 files changed, 63 insertions(+)
> 
> diff --git a/app/test/test_prefetch.c b/app/test/test_prefetch.c index
> 41f219a..5c58d0c 100644
> --- a/app/test/test_prefetch.c
> +++ b/app/test/test_prefetch.c
> @@ -26,7 +26,11 @@
>  	rte_prefetch1(&a);
>  	rte_prefetch2(&a);
> 
> +/* test for marking a line as shared to test cldemote functionality */
> +	rte_cldemote(&a);
> +
>  	return 0;
>  }
> 
> +
>  REGISTER_TEST_COMMAND(prefetch_autotest, test_prefetch); diff --git
> a/doc/guides/rel_notes/release_20_11.rst
> b/doc/guides/rel_notes/release_20_11.rst
> index df227a1..dc402ab 100644
> --- a/doc/guides/rel_notes/release_20_11.rst
> +++ b/doc/guides/rel_notes/release_20_11.rst
> @@ -55,6 +55,13 @@ New Features
>       Also, make sure to start the actual text at the margin.
>       =======================================================
> 
> +* **Added new function rte_cldemote in rte_prefetch.h.**
> +
> +  Added a hardware hint CLDEMOTE, which is similar to prefetch in reverse.
> +  CLDEMOTE moves the cache line to the more remote cache, where it
> + expects  sharing to be efficient. Moving the cache line to a level
> + more distant from  the processor helps to accelerate core-to-core
> communication.
> +

Patch cannot apply. Maybe rebase is needed.

> 
>  Removed Items
>  -------------
> diff --git a/lib/librte_eal/arm/include/rte_prefetch_32.h
> b/lib/librte_eal/arm/include/rte_prefetch_32.h
> index e53420a..062ed27 100644
> --- a/lib/librte_eal/arm/include/rte_prefetch_32.h
> +++ b/lib/librte_eal/arm/include/rte_prefetch_32.h
> @@ -10,6 +10,7 @@
>  #endif
> 
>  #include <rte_common.h>
> +#include <rte_compat.h>
>  #include "generic/rte_prefetch.h"
> 
>  static inline void rte_prefetch0(const volatile void *p) @@ -33,6 +34,13 @@
> static inline void rte_prefetch_non_temporal(const volatile void *p)
>  	rte_prefetch0(p);
>  }
> 
> +static inline void
> +__rte_experimental

See below.

> +rte_cldemote(const volatile void *p)
> +{
> +	RTE_SET_USED(p);
> +}
> +
>  #ifdef __cplusplus
>  }
>  #endif
> diff --git a/lib/librte_eal/arm/include/rte_prefetch_64.h
> b/lib/librte_eal/arm/include/rte_prefetch_64.h
> index fc2b391..6e5ee07 100644
> --- a/lib/librte_eal/arm/include/rte_prefetch_64.h
> +++ b/lib/librte_eal/arm/include/rte_prefetch_64.h
> @@ -10,6 +10,7 @@
>  #endif
> 
>  #include <rte_common.h>
> +#include <rte_compat.h>
>  #include "generic/rte_prefetch.h"
> 
>  static inline void rte_prefetch0(const volatile void *p) @@ -32,6 +33,13 @@
> static inline void rte_prefetch_non_temporal(const volatile void *p)
>  	asm volatile ("PRFM PLDL1STRM, [%0]" : : "r" (p));  }
> 
> +static inline void
> +__rte_experimental
> +rte_cldemote(const volatile void *p)
> +{
> +	RTE_SET_USED(p);
> +}
> +
>  #ifdef __cplusplus
>  }
>  #endif
> diff --git a/lib/librte_eal/include/generic/rte_prefetch.h
> b/lib/librte_eal/include/generic/rte_prefetch.h
> index 6e47bdf..3474548 100644
> --- a/lib/librte_eal/include/generic/rte_prefetch.h
> +++ b/lib/librte_eal/include/generic/rte_prefetch.h
> @@ -51,4 +51,20 @@
>   */
>  static inline void rte_prefetch_non_temporal(const volatile void *p);
> 
> +/**
> + * Demote a cache line to a more distant level of cache from the processor.
> + *
> + * CLDEMOTE hints to hardware to move (demote) a cache line from the
> +closest to
> + * the processor to a level more distant from the processor. It is a
> +hint and
> + * not guarantee. rte_cldemote is intended to move the cache line to
> +the more
> + * remote cache, where it expects sharing to be efficient and to
> +indicate that a
> + * line may be accessed by a different core in the future.
> + *
> + * @param p
> + *   Address to demote
> + */
> +static inline void
> +__rte_experimental

1. Experimental tag is only needed in this file. Tags at other places can be removed.
2. To align with other codes, experimental tag can be put above 'static inline void' line.

> +rte_cldemote(const volatile void *p);
> +
>  #endif /* _RTE_PREFETCH_H_ */
> diff --git a/lib/librte_eal/ppc/include/rte_prefetch.h
> b/lib/librte_eal/ppc/include/rte_prefetch.h
> index 9ba07c8..9630227 100644
> --- a/lib/librte_eal/ppc/include/rte_prefetch.h
> +++ b/lib/librte_eal/ppc/include/rte_prefetch.h
> @@ -11,6 +11,7 @@
>  #endif
> 
>  #include <rte_common.h>
> +#include <rte_compat.h>
>  #include "generic/rte_prefetch.h"
> 
>  static inline void rte_prefetch0(const volatile void *p) @@ -34,6 +35,13 @@
> static inline void rte_prefetch_non_temporal(const volatile void *p)
>  	rte_prefetch0(p);
>  }
> 
> +static inline void
> +__rte_experimental
> +rte_cldemote(const volatile void *p)
> +{
> +	RTE_SET_USED(p);
> +}
> +
>  #ifdef __cplusplus
>  }
>  #endif
> diff --git a/lib/librte_eal/x86/include/rte_prefetch.h
> b/lib/librte_eal/x86/include/rte_prefetch.h
> index 384c6b3..e1e120e 100644
> --- a/lib/librte_eal/x86/include/rte_prefetch.h
> +++ b/lib/librte_eal/x86/include/rte_prefetch.h
> @@ -10,6 +10,7 @@
>  #endif
> 
>  #include <rte_common.h>
> +#include <rte_compat.h>
>  #include "generic/rte_prefetch.h"
> 
>  static inline void rte_prefetch0(const volatile void *p) @@ -32,6 +33,17 @@
> static inline void rte_prefetch_non_temporal(const volatile void *p)
>  	asm volatile ("prefetchnta %[p]" : : [p] "m" (*(const volatile char
> *)p));  }
> 
> +/*
> + * we're using raw byte codes for now as only the newest compiler
> + * versions support this instruction natively.
> + */
> +static inline void
> +__rte_experimental
> +rte_cldemote(const volatile void *p)
> +{
> +	asm volatile(".byte 0x0f, 0x1c, 0x06" :: "S" (p)); }
> +
>  #ifdef __cplusplus
>  }
>  #endif
> --
> 1.8.3.1


  parent reply	other threads:[~2020-10-13  2:59 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-10  1:16 [dpdk-dev] [PATCH] EAL: An addition of cache line demote (CLDEMOTE) in rte_prefetch.h Omkar Maslekar
2020-09-10  1:16 ` Omkar Maslekar
2020-09-10  8:55   ` Bruce Richardson
2020-09-10 23:30     ` Maslekar, Omkar
2020-09-10 22:04   ` David Christensen
2020-09-11 16:51 ` [dpdk-dev] [PATCH v2] " Omkar Maslekar
2020-09-11 16:51   ` Omkar Maslekar
2020-09-11 21:22 ` [dpdk-dev] [PATCH v3] " Omkar Maslekar
2020-09-11 21:22   ` Omkar Maslekar
2020-09-22  1:59 ` [dpdk-dev] [PATCH v4] eal: add cache-line demote support Omkar Maslekar
2020-09-22  1:59   ` Omkar Maslekar
2020-09-22  8:28     ` Bruce Richardson
2020-09-22 21:53       ` Maslekar, Omkar
2020-10-01  0:28 ` [dpdk-dev] [PATCH v5] " Omkar Maslekar
2020-10-01  0:28   ` Omkar Maslekar
2020-10-08  7:09     ` David Marchand
2020-10-08  9:02       ` Bruce Richardson
2020-10-12  9:41         ` David Marchand
2020-10-08 13:12     ` Jerin Jacob
2020-10-12 10:19 ` [dpdk-dev] [PATCH v6] " Omkar Maslekar
2020-10-12 10:19   ` Omkar Maslekar
2020-10-12 19:31     ` David Christensen
2020-10-13  2:59     ` Ruifeng Wang [this message]
2020-10-13 16:20       ` Bruce Richardson
2020-10-14  1:55         ` Ruifeng Wang
2020-10-14  7:14         ` David Marchand
2020-10-14  7:51           ` Ruifeng Wang
2020-10-13  9:43 ` [dpdk-dev] [PATCH v7] " Omkar Maslekar
2020-10-13  9:43   ` Omkar Maslekar
2020-10-14  7:24     ` Ruifeng Wang
2020-10-15  8:01     ` David Marchand
2020-10-15 14:41       ` Maslekar, Omkar
2020-10-15 20:32         ` David Marchand
2020-10-15 15:18 ` [dpdk-dev] [PATCH v8] " Omkar Maslekar
2020-10-15 15:18   ` Omkar Maslekar
2020-10-15 23:20 ` [dpdk-dev] [PATCH v9] " Omkar Maslekar
2020-10-15 23:20   ` Omkar Maslekar
2020-10-16 12:14     ` David Marchand

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=HE1PR0802MB234538D6A7FD6A76586EC8849E040@HE1PR0802MB2345.eurprd08.prod.outlook.com \
    --to=ruifeng.wang@arm.com \
    --cc=Honnappa.Nagarahalli@arm.com \
    --cc=bruce.richardson@intel.com \
    --cc=ciara.loftus@intel.com \
    --cc=dev@dpdk.org \
    --cc=drc@linux.vnet.ibm.com \
    --cc=jerinj@marvell.com \
    --cc=nd@arm.com \
    --cc=omkar.maslekar@intel.com \
    /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

DPDK patches and discussions

This inbox may be cloned and mirrored by anyone:

	git clone --mirror https://inbox.dpdk.org/dev/0 dev/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 dev dev/ https://inbox.dpdk.org/dev \
		dev@dpdk.org
	public-inbox-index dev

Example config snippet for mirrors.
Newsgroup available over NNTP:
	nntp://inbox.dpdk.org/inbox.dpdk.dev


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git