DPDK patches and discussions
 help / color / mirror / Atom feed
From: Jerin Jacob Kollanukkaran <jerinj@marvell.com>
To: "stephen@networkplumber.org" <stephen@networkplumber.org>
Cc: "david.marchand@redhat.com" <david.marchand@redhat.com>,
	"chaozhu@linux.vnet.ibm.com" <chaozhu@linux.vnet.ibm.com>,
	"nd@arm.com" <nd@arm.com>,
	"bruce.richardson@intel.com" <bruce.richardson@intel.com>,
	"thomas@monjalon.net" <thomas@monjalon.net>,
	"dev@dpdk.org" <dev@dpdk.org>,
	"Joyce.Kong@arm.com" <Joyce.Kong@arm.com>,
	"hemant.agrawal@nxp.com" <hemant.agrawal@nxp.com>,
	"Honnappa.Nagarahalli@arm.com" <Honnappa.Nagarahalli@arm.com>,
	"Gavin.Hu@arm.com" <Gavin.Hu@arm.com>
Subject: Re: [dpdk-dev] [EXT] [PATCH v3 6/6] spinlock: ticket based to improve fairness
Date: Fri, 28 Dec 2018 04:39:01 +0000	[thread overview]
Message-ID: <7918c83453f4d57af83c5b79eae2932a8bf5173f.camel@marvell.com> (raw)
In-Reply-To: <20181227154143.7eb56fcc@shemminger-XPS-13-9360>

On Thu, 2018-12-27 at 15:41 -0800, Stephen Hemminger wrote:
> On Thu, 27 Dec 2018 12:08:26 +0000
> Jerin Jacob Kollanukkaran <jerinj@marvell.com> wrote:
> 
> > On Thu, 2018-12-27 at 10:05 +0000, Gavin Hu (Arm Technology China)
> > wrote:
> > > > -----Original Message-----
> > > > From: Jerin Jacob Kollanukkaran <jerinj@marvell.com>
> > > > Sent: Thursday, December 27, 2018 2:58 PM
> > > > To: Gavin Hu (Arm Technology China) <Gavin.Hu@arm.com>; 
> > > > dev@dpdk.org
> > > > Cc: david.marchand@redhat.com; chaozhu@linux.vnet.ibm.com; nd
> > > > <nd@arm.com>; bruce.richardson@intel.com; thomas@monjalon.net;
> > > > Joyce
> > > > Kong (Arm Technology China) <Joyce.Kong@arm.com>;
> > > > hemant.agrawal@nxp.com; stephen@networkplumber.org; Honnappa
> > > > Nagarahalli <Honnappa.Nagarahalli@arm.com>
> > > > Subject: Re: [EXT] [PATCH v3 6/6] spinlock: ticket based to
> > > > improve
> > > > fairness
> > > > 
> > > > On Thu, 2018-12-27 at 12:13 +0800, Gavin Hu wrote:  
> > > > > -----------------------------------------------------------
> > > > > ----
> > > > > ----
> > > > > ---
> > > > > From: Joyce Kong <joyce.kong@arm.com>
> > > > > 
> > > > > The old implementation is unfair, some threads may take locks
> > > > > aggressively  
> > > > 
> > > > I think, one issue here is x86 and ppc follows traditional
> > > > spinlock
> > > > and
> > > > arm64 will be following ticket lock for spinlock
> > > > implementation.
> > > > This would change application behaviour on arm64 compared to
> > > > x86
> > > > and
> > > > ppc.
> > > > 
> > > > How about having a separate API for ticket lock? That would
> > > > give,
> > > > # application choice to use the locking strategy
> > > > # application behaviour will be same across all arch.  
> > > 
> > > Ok, will do in v4 to have a new named rte_ticket_spinlock API.  
> > 
> > I would prefer rte_ticketlock_[lock/unlock/trylock/is_locked] name
> > instead of rte_ticket_spinlock_lock etc to reduce the length of the
> > API.
> 
> NAK to adding new API for this.
> 
> I want the best possible locks for all applications and all
> architectures.
> These should be called spinlock so there is no requirement for
> application
> to change to get better performance. Why not just implement the best
> algorithm
> across the board. Yes, this means collaboration or working on the
> other guys
> architecture.

Then 6/6 patch needs to put on hold if every arch needs to make ticket
lock as default spinlock lock strategy.

How about following to make forward progress:
1) Introduce rte_ticketlock_[lock/unlock/trylock/is_locked] API now as
experimental with default implementation
2) Provide a time line to switch every arch for optimized ticketlock
implementation if needed.
3) Switch rte_ticketlock_ as rte_spinlock_ API.
4) Keep old version of spinlock as new API if some application does not
need fairness between threads at the cost of light weight spinlock
implementation.

I don't want arm64 to behave differently than other arch(s).









  reply	other threads:[~2018-12-28  4:39 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-27  4:13 [dpdk-dev] [PATCH v3 0/6] spinlock optimization and test case enhancements Gavin Hu
2018-12-27  4:13 ` [dpdk-dev] [PATCH v3 1/6] eal: fix clang compilation error on x86 Gavin Hu
2018-12-27  6:36   ` [dpdk-dev] [EXT] " Jerin Jacob Kollanukkaran
2018-12-27  4:13 ` [dpdk-dev] [PATCH v3 2/6] test/spinlock: remove 1us delay for correct benchmarking Gavin Hu
2018-12-27  7:20   ` [dpdk-dev] [EXT] " Jerin Jacob Kollanukkaran
2018-12-27  4:13 ` [dpdk-dev] [PATCH v3 3/6] test/spinlock: get timestamp more precisely Gavin Hu
2018-12-27  7:27   ` [dpdk-dev] [EXT] " Jerin Jacob Kollanukkaran
2019-01-03 18:22     ` Honnappa Nagarahalli
2018-12-27  4:13 ` [dpdk-dev] [PATCH v3 4/6] test/spinlock: amortize the cost of getting time Gavin Hu
2018-12-27  4:13 ` [dpdk-dev] [PATCH v3 5/6] spinlock: reimplement with atomic one-way barrier builtins Gavin Hu
2018-12-27  7:42   ` [dpdk-dev] [EXT] " Jerin Jacob Kollanukkaran
2018-12-27  9:02     ` Gavin Hu (Arm Technology China)
2019-01-03 20:35       ` Honnappa Nagarahalli
2019-01-11 13:52     ` Gavin Hu (Arm Technology China)
2019-01-14  5:54       ` Honnappa Nagarahalli
2019-01-14  7:39         ` Jerin Jacob Kollanukkaran
2019-01-14 17:08           ` Gavin Hu (Arm Technology China)
2019-01-14  7:57         ` Gavin Hu (Arm Technology China)
2018-12-27  4:13 ` [dpdk-dev] [PATCH v3 6/6] spinlock: ticket based to improve fairness Gavin Hu
2018-12-27  6:58   ` [dpdk-dev] [EXT] " Jerin Jacob Kollanukkaran
2018-12-27 10:05     ` Gavin Hu (Arm Technology China)
2018-12-27 12:08       ` Jerin Jacob Kollanukkaran
2018-12-27 23:41         ` Stephen Hemminger
2018-12-28  4:39           ` Jerin Jacob Kollanukkaran [this message]
2018-12-28 10:04             ` Gavin Hu (Arm Technology China)
2019-01-03 18:35             ` Honnappa Nagarahalli
2019-01-03 19:53               ` Stephen Hemminger
2019-01-04  7:06                 ` Honnappa Nagarahalli

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=7918c83453f4d57af83c5b79eae2932a8bf5173f.camel@marvell.com \
    --to=jerinj@marvell.com \
    --cc=Gavin.Hu@arm.com \
    --cc=Honnappa.Nagarahalli@arm.com \
    --cc=Joyce.Kong@arm.com \
    --cc=bruce.richardson@intel.com \
    --cc=chaozhu@linux.vnet.ibm.com \
    --cc=david.marchand@redhat.com \
    --cc=dev@dpdk.org \
    --cc=hemant.agrawal@nxp.com \
    --cc=nd@arm.com \
    --cc=stephen@networkplumber.org \
    --cc=thomas@monjalon.net \
    /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).