DPDK patches and discussions
 help / color / mirror / Atom feed
From: Thomas Monjalon <thomas@monjalon.net>
To: Jerin Jacob <jerinjacobk@gmail.com>
Cc: David Marchand <david.marchand@redhat.com>,
	dpdk-dev <dev@dpdk.org>, Jerin Jacob <jerinj@marvell.com>,
	Sunil Kumar Kori <skori@marvell.com>,
	John McNamara <john.mcnamara@intel.com>,
	Marko Kovacevic <marko.kovacevic@intel.com>,
	Declan Doherty <declan.doherty@intel.com>,
	Ferruh Yigit <ferruh.yigit@intel.com>,
	Andrew Rybchenko <arybchenko@solarflare.com>,
	Olivier Matz <olivier.matz@6wind.com>
Subject: Re: [dpdk-dev] [PATCH 2/8] trace: simplify trace point registration
Date: Tue, 05 May 2020 09:01:48 +0200
Message-ID: <2596990.BEx9A2HvPv@thomas> (raw)
In-Reply-To: <CALBAE1MePBx5j56Z8-TbjP2RzzDWRZfFXjTrd1Z-Ydtu+WvQ-w@mail.gmail.com>

05/05/2020 05:43, Jerin Jacob:
> On Tue, May 5, 2020 at 3:01 AM Thomas Monjalon <thomas@monjalon.net> wrote:
> > 04/05/2020 19:54, Jerin Jacob:
> > > On Mon, May 4, 2020 at 11:10 PM David Marchand
> > > > On Mon, May 4, 2020 at 7:19 PM Jerin Jacob <jerinjacobk@gmail.com> wrote:
> > > > > On Mon, May 4, 2020 at 10:38 PM David Marchand
> > > > > > On Mon, May 4, 2020 at 4:39 PM Jerin Jacob <jerinjacobk@gmail.com> wrote:
> > > > > > > On Mon, May 4, 2020 at 7:34 PM David Marchand <david.marchand@redhat.com> wrote:
> > > > > > > > On Mon, May 4, 2020 at 4:47 AM Jerin Jacob <jerinjacobk@gmail.com> wrote:
> > > > > > > > > On Mon, May 4, 2020 at 2:02 AM David Marchand <david.marchand@redhat.com> wrote:
> > > > > > > > > >
> > > > > > > > > > RTE_TRACE_POINT_DEFINE and RTE_TRACE_POINT_REGISTER must come in pairs.
> > > > > > > > > > Merge them and let RTE_TRACE_POINT_REGISTER handle the constructor part.
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > Initially, I thought of doing the same. But, later I realized that
> > > > > > > > > this largely grows the number of constructors been called.
> > > > > > > > > I had concerns about the boot time of the application and/or loading
> > > > > > > > > the shared library, that the reason why spitting
> > > > > > > > > as two so that constructor registers a burst of traces like rte_log.
> > > > > > > >
> > > > > > > > I am a bit skeptical.
> > > > > > > > In terms of cycles and looking at __rte_trace_point_register() (which
> > > > > > > > calls malloc), the cost of calling multiple constructors instead of
> > > > > > > > one is negligible.
> > > > > > >
> > > > > > > We will have a lot tracepoints latter, each one translates to the
> > > > > > > constructor may not be a good
> > > > > > > improvement. The scope is limited only to register function so IMO it
> > > > > > > is okay to have split
> > > > > > > just like rte_log. I don't see any reason why it has to be a different
> > > > > > > than rte_log.
> > > > > >
> > > > > > What is similar to rte_log?
> > > > > > There is neither RTE_LOG_REGISTER macro, nor two-steps declaration of
> > > > > > dynamic logtypes.
> > > > >
> > > > >
> > > > > Here is an example of rte_log registration. Which has _one_
> > > > > constructor and N number of
> > > > > rte_log_register() underneath.
> > > >
> > > > rte_log is one thing, rte_trace is already different.
> > > >
> > > > There is _no macro_ in rte_log for registration.
> > > > The reason being in that a rte_log logtype is a simple integer without
> > > > any special declaration requiring a macro.
> > >
> > > I just wrapped in macro for convincing, but it has the same semantics.
> > > global variable and API/macro to register.
> > >
> > >
> > > >
> > > > For tracepoints, we have a special two steps thing: the tracepoint
> > > > handle must be derived from the tracepoint name.
> > > > Then this handle must be registered.
> > > > What I proposed is to make life easier for developers that want to add
> > > > tracepoints and I suppose you noticed patch 1 of this series.
> > >
> > > To reduce the constructors. I don't want trace libraries to add lot of
> > > constructors.
> > > I don't think it simplifies a lot as the scope of only for registration.
> > >
> > >
> > > >
> > > >
> > > > > > > One of the thought process is, we probably remove the constructor
> > > > > > > scheme to all other with DPDK
> > > > > > > and replace it with a more register scheme. In such a case, we can
> > > > > > > skip calling the constructor all tother
> > > > > > > when trace is disabled.
> > > > > >
> > > > > > Sorry, but I have a hard time understanding your point.
> > > > > > Are you talking about application boot time?
> > > > >
> > > > > Yes. The optimization of application boottime time in case of static
> > > > > binary and/or shared library(.so) load time.
> > > >
> > > > As Thomas mentioned, do you have numbers?
> > >
> > > No. But I know, it is obvious that current code is better in terms of
> > > boot time than the proposed one.
> > > I would like to not add a lot of constructor for trace as the FIRST
> > > module in DPDK.
> >
> > No, it is not obvious.
> > The version from David looks simpler to use and to understand.
> > Without any number, I consider usability (and maintenance) wins.
> 
> Thanks for the feedback.
> 
> As the trace maintainer, I would like not to explode constructor usage
> for trace library.
> My reasoning, We could do trace registration without this constructor scheme.

???


> If you think, it is better usability, lets add an option for rte_log
> for the constructor scheme.

It makes non-sense.
rte_log requires only one function call per log type.
rte_trace requires 3 macros calls per trace type:
RTE_TRACE_POINT_REGISTER, RTE_TRACE_POINT_DEFINE, RTE_TRACE_POINT_ARGS

This patch is unifying the first 2 macro calls to make usage simpler,
and ease rte_trace adoption.

Note: the other usability weirdness is mandating declaring each trace
function with a magic double underscore prefix which appears nowhere else.


> Analyze the impact wrt boot time and cross-platform pov as the log
> has a lot of entries to test. If the usage makes sense then it should make sense
> for rte_log too. I would like to NOT have trace to be the first
> library to explode
> with the constructor scheme. I suggest removing this specific patch from RC2 and
> revisit later.

You still did not give any argument against increasing the number
of constructors.



  reply	other threads:[~2020-05-05  7:01 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-03 20:31 [dpdk-dev] [PATCH 0/8] Traces cleanup for rc2 David Marchand
2020-05-03 20:31 ` [dpdk-dev] [PATCH 1/8] cryptodev: fix trace points registration David Marchand
2020-05-04  7:41   ` [dpdk-dev] [EXT] " Sunil Kumar Kori
2020-05-03 20:31 ` [dpdk-dev] [PATCH 2/8] trace: simplify trace point registration David Marchand
2020-05-04  2:46   ` Jerin Jacob
2020-05-04 14:02     ` Thomas Monjalon
2020-05-04 14:04     ` David Marchand
2020-05-04 14:39       ` Jerin Jacob
2020-05-04 17:08         ` David Marchand
2020-05-04 17:19           ` Jerin Jacob
2020-05-04 17:40             ` David Marchand
2020-05-04 17:54               ` Jerin Jacob
2020-05-04 21:31                 ` Thomas Monjalon
2020-05-05  3:43                   ` Jerin Jacob
2020-05-05  7:01                     ` Thomas Monjalon [this message]
2020-05-05  7:17                       ` Jerin Jacob
2020-05-05  7:24                         ` Thomas Monjalon
2020-05-05  7:33                           ` Jerin Jacob
2020-05-05  8:23                             ` David Marchand
2020-05-05 10:12                               ` Jerin Jacob
2020-05-05 10:26                                 ` Thomas Monjalon
2020-05-05 10:46                                   ` Jerin Jacob
2020-05-05 11:48                                     ` Olivier Matz
2020-05-05 11:35                                 ` David Marchand
2020-05-05 12:26                                   ` Jerin Jacob
2020-05-05 15:25                                     ` Jerin Jacob
2020-05-05 16:28                                       ` David Marchand
2020-05-05 16:46                                         ` Jerin Jacob
2020-05-05 16:58                                           ` Thomas Monjalon
2020-05-05 17:08                                             ` Jerin Jacob
2020-05-05 17:09                                               ` Jerin Jacob
2020-05-05 17:20                                                 ` Thomas Monjalon
2020-05-05 17:28                                                   ` Jerin Jacob
2020-05-05 20:10                                                     ` Thomas Monjalon
2020-05-06  6:11                                                       ` Jerin Jacob
2020-07-04 14:31   ` Jerin Jacob
2020-07-04 15:14   ` [dpdk-dev] [PATCH v2] " David Marchand
2020-07-05 19:41     ` Thomas Monjalon
2020-05-03 20:31 ` [dpdk-dev] [PATCH 3/8] trace: simplify trace point headers David Marchand
2020-05-04  6:12   ` Jerin Jacob
2020-05-03 20:31 ` [dpdk-dev] [PATCH 4/8] trace: avoid confusion on optarg David Marchand
2020-05-04  7:55   ` [dpdk-dev] [EXT] " Sunil Kumar Kori
2020-05-04 14:09     ` David Marchand
2020-05-05  5:45       ` Sunil Kumar Kori
2020-05-05  5:47         ` Sunil Kumar Kori
2020-05-03 20:31 ` [dpdk-dev] [PATCH 5/8] trace: remove unneeded checks in internal API David Marchand
2020-05-04  8:16   ` [dpdk-dev] [EXT] " Sunil Kumar Kori
2020-05-03 20:31 ` [dpdk-dev] [PATCH 6/8] trace: remove limitation on patterns number David Marchand
2020-05-04  8:48   ` [dpdk-dev] [EXT] " Sunil Kumar Kori
2020-05-04 14:14     ` David Marchand
2020-05-05  5:54       ` Sunil Kumar Kori
2020-05-03 20:31 ` [dpdk-dev] [PATCH 7/8] trace: remove string duplication David Marchand
2020-05-04  9:01   ` [dpdk-dev] [EXT] " Sunil Kumar Kori
2020-05-03 20:31 ` [dpdk-dev] [PATCH 8/8] trace: fix build with gcc 10 David Marchand
2020-05-06 13:06 ` [dpdk-dev] [PATCH 0/8] Traces cleanup for rc2 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=2596990.BEx9A2HvPv@thomas \
    --to=thomas@monjalon.net \
    --cc=arybchenko@solarflare.com \
    --cc=david.marchand@redhat.com \
    --cc=declan.doherty@intel.com \
    --cc=dev@dpdk.org \
    --cc=ferruh.yigit@intel.com \
    --cc=jerinj@marvell.com \
    --cc=jerinjacobk@gmail.com \
    --cc=john.mcnamara@intel.com \
    --cc=marko.kovacevic@intel.com \
    --cc=olivier.matz@6wind.com \
    --cc=skori@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