DPDK patches and discussions
 help / color / mirror / Atom feed
From: "Van Haaren, Harry" <harry.van.haaren@intel.com>
To: Pavan Nikhilesh Bhagavatula <pbhagavatula@marvell.com>,
	"dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH] eal: add new prefetch0_write variant
Date: Mon, 14 Sep 2020 08:12:23 +0000
Message-ID: <BYAPR11MB3143B6143122A830F58345AFD7230@BYAPR11MB3143.namprd11.prod.outlook.com> (raw)
In-Reply-To: <BN6PR18MB11402D4A8AB0E722D902D3BFDE220@BN6PR18MB1140.namprd18.prod.outlook.com>

> -----Original Message-----
> From: Pavan Nikhilesh Bhagavatula <pbhagavatula@marvell.com>
> Sent: Sunday, September 13, 2020 9:11 PM
> To: Van Haaren, Harry <harry.van.haaren@intel.com>; dev@dpdk.org
> Subject: RE: [dpdk-dev] [PATCH] eal: add new prefetch0_write variant
> 
> >This commit adds a new rte_prefetch0_write() variant, suggests to the
> >compiler to use a prefetch instruction with intention to write. As a
> >compiler builtin, the compiler can choose based on compilation target
> >what the best implementation for this instruction is.
> 
> Why not have the other variants too i.e. l2/l3/temporal store prefetches too?

Hi Pavan,

Are there architectures that actually implement those? Usually for a WB mem store to complete,
the data must be present in L1 cache (on x86 at least), and that's what the patch below with write0 achieves.

I'm against adding all the variants "just in case", it leads to API bloat, and increases
cognitive load on the programmer. My expectation is that in 99% of usage the prefetch
write instruction should target L1.

Cheers, -Harry

> >Signed-off-by: Harry van Haaren <harry.van.haaren@intel.com>
> >
> >---
> >
> >The integer constants passed to the builtin are not available as
> >a #define value, and doing #defines just for this write variant
> >does not seems a nice solution to me... particularly for those using
> >IDEs where any #define value is auto-hinted for code-completion.
> >
> >---
> > lib/librte_eal/include/generic/rte_prefetch.h | 16 ++++++++++++++++
> > 1 file changed, 16 insertions(+)

<snip patch contents>


  reply	other threads:[~2020-09-14  8:12 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-11  9:19 Harry van Haaren
2020-09-13 20:11 ` Pavan Nikhilesh Bhagavatula
2020-09-14  8:12   ` Van Haaren, Harry [this message]
2020-09-14 10:39     ` Pavan Nikhilesh Bhagavatula
2020-09-14 15:10       ` Van Haaren, Harry
2020-09-14 15:10 ` [dpdk-dev] [PATCH v2] eal: add new prefetch write variants Harry van Haaren
2020-10-08  7:42   ` David Marchand
2020-10-08  8:34     ` Van Haaren, Harry
2020-10-08  8:39       ` Van Haaren, Harry
2020-10-08  8:54   ` Jerin Jacob
2020-10-10 10:21   ` Ruifeng Wang
2020-10-15  8:18   ` David Marchand
2020-10-15  8:44     ` Van Haaren, Harry
2020-10-15 10:32   ` [dpdk-dev] [PATCH v3] " Harry van Haaren
2020-10-15 20:27     ` 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=BYAPR11MB3143B6143122A830F58345AFD7230@BYAPR11MB3143.namprd11.prod.outlook.com \
    --to=harry.van.haaren@intel.com \
    --cc=dev@dpdk.org \
    --cc=pbhagavatula@marvell.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