DPDK patches and discussions
 help / color / mirror / Atom feed
From: Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>
To: "Van Haaren, Harry" <harry.van.haaren@intel.com>,
	"Richardson, Bruce" <bruce.richardson@intel.com>,
	"Wang, Yipeng1" <yipeng1.wang@intel.com>
Cc: "De Lara Guarch, Pablo" <pablo.de.lara.guarch@intel.com>,
	"dev@dpdk.org" <dev@dpdk.org>,
	"Gavin Hu (Arm Technology China)" <Gavin.Hu@arm.com>,
	Steve Capper <Steve.Capper@arm.com>,
	Ola Liljedahl <Ola.Liljedahl@arm.com>, nd <nd@arm.com>
Subject: Re: [dpdk-dev] [PATCH 3/4] hash: fix rw concurrency while moving	keys
Date: Sun, 30 Sep 2018 22:33:14 +0000	[thread overview]
Message-ID: <AM6PR08MB3672C2D99F8B58A027AA65FB98EE0@AM6PR08MB3672.eurprd08.prod.outlook.com> (raw)
In-Reply-To: <E923DB57A917B54B9182A2E928D00FA65E2E0E47@IRSMSX102.ger.corp.intel.com>


> > > >
> > > >Reader-writer concurrency issue, caused by moving the keys to their
> > > >alternative locations during key insert, is solved by introducing a
> > > >global counter(tbl_chng_cnt) indicating a change in table.
> 
> <snip>
> 
> > > > /**
> > > >@@ -200,7 +200,7 @@ rte_hash_add_key_with_hash_data(const struct
> > > >rte_hash
> > *h, const void *key,
> > > >  *     array of user data. This value is unique for this key.
> > > >  */
> > > > int32_t
> > > >-rte_hash_add_key(const struct rte_hash *h, const void *key);
> > > >+rte_hash_add_key(struct rte_hash *h, const void *key);
> > > >
> > > > /**
> > > >  * Add a key to an existing hash table.
> > > >@@ -222,7 +222,7 @@ rte_hash_add_key(const struct rte_hash *h,
> > > >const void
> > *key);
> > > >  *     array of user data. This value is unique for this key.
> > > >  */
> > > > int32_t
> > > >-rte_hash_add_key_with_hash(const struct rte_hash *h, const void
> > > >*key,
> > hash_sig_t sig);
> > > >+rte_hash_add_key_with_hash(struct rte_hash *h, const void *key,
> > hash_sig_t sig);
> > > >
> > > > /
> > >
> > > I think the above changes will break ABI by changing the parameter type?
> > Other people may know better on this.
> >
> > Just removing a const should not change the ABI, I believe, since the
> > const is just advisory hint to the compiler. Actual parameter size and
> > count remains unchanged so I don't believe there is an issue.
> > [ABI experts, please correct me if I'm wrong on this]
> 
> 
> [Certainly no ABI expert, but...]
> 
> I think this is an API break, not ABI break.
> 
> Given application code as follows, it will fail to compile - even though running
> the new code as a .so wouldn't cause any issues (AFAIK).
> 
> void do_hash_stuff(const struct rte_hash *h, ...) {
>     /* parameter passed in is const, but updated function prototype is non-
> const */
>     rte_hash_add_key_with_hash(h, ...);
> }
> 
> This means that we can't recompile apps against latest patch without
> application code changes, if the app was passing a const rte_hash struct as
> the first parameter.
> 
Agree. Do we need to do anything for this?

> 
> -Harry

  reply	other threads:[~2018-09-30 22:33 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-06 17:12 [dpdk-dev] [PATCH 0/4] Address reader-writer concurrency in rte_hash Honnappa Nagarahalli
2018-09-06 17:12 ` [dpdk-dev] [PATCH 1/4] hash: correct key store element alignment Honnappa Nagarahalli
2018-09-27 23:58   ` Wang, Yipeng1
2018-09-06 17:12 ` [dpdk-dev] [PATCH 2/4] hash: add memory ordering to avoid race conditions Honnappa Nagarahalli
2018-09-28  0:43   ` Wang, Yipeng1
2018-09-30 22:20     ` Honnappa Nagarahalli
2018-10-01 22:41       ` Wang, Yipeng1
2018-10-01 10:42     ` Ola Liljedahl
2018-10-02  1:52       ` Wang, Yipeng1
2018-09-06 17:12 ` [dpdk-dev] [PATCH 3/4] hash: fix rw concurrency while moving keys Honnappa Nagarahalli
2018-09-28  1:00   ` Wang, Yipeng1
2018-09-28  8:26     ` Bruce Richardson
2018-09-28  8:55       ` Van Haaren, Harry
2018-09-30 22:33         ` Honnappa Nagarahalli [this message]
2018-10-02 13:17           ` Van Haaren, Harry
2018-10-02 23:58             ` Wang, Yipeng1
2018-10-03 17:32               ` Honnappa Nagarahalli
2018-10-03 17:56                 ` Wang, Yipeng1
2018-10-03 23:05                   ` Ola Liljedahl
2018-10-04  3:32                   ` Honnappa Nagarahalli
2018-10-04  3:54                 ` Honnappa Nagarahalli
2018-10-04 19:16                   ` Wang, Yipeng1
2018-09-30 23:05     ` Honnappa Nagarahalli
2018-10-01 22:56       ` Wang, Yipeng1
2018-10-03  0:16       ` Wang, Yipeng1
2018-10-03 17:39         ` Honnappa Nagarahalli
2018-09-06 17:12 ` [dpdk-dev] [PATCH 4/4] hash: enable lock-free reader-writer concurrency Honnappa Nagarahalli
2018-09-28  1:33   ` Wang, Yipeng1
2018-10-01  4:11     ` Honnappa Nagarahalli
2018-10-01 23:54       ` Wang, Yipeng1
2018-10-11  5:24         ` Honnappa Nagarahalli
2018-09-14 21:18 ` [dpdk-dev] [PATCH 0/4] Address reader-writer concurrency in rte_hash Honnappa Nagarahalli
2018-09-26 14:36   ` Honnappa Nagarahalli
2018-09-27 23:45 ` Wang, Yipeng1
2018-09-28 21:11   ` Honnappa Nagarahalli
2018-10-02  0:30     ` Wang, Yipeng1

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=AM6PR08MB3672C2D99F8B58A027AA65FB98EE0@AM6PR08MB3672.eurprd08.prod.outlook.com \
    --to=honnappa.nagarahalli@arm.com \
    --cc=Gavin.Hu@arm.com \
    --cc=Ola.Liljedahl@arm.com \
    --cc=Steve.Capper@arm.com \
    --cc=bruce.richardson@intel.com \
    --cc=dev@dpdk.org \
    --cc=harry.van.haaren@intel.com \
    --cc=nd@arm.com \
    --cc=pablo.de.lara.guarch@intel.com \
    --cc=yipeng1.wang@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
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).