linux-kernel - RE: [RFC PATCH 2/7] RDMA/rxe: Convert the triple tasklets to workqueues

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <TYCPR01MB8455D739FC9FB034E3485C87E5449@TYCPR01MB8455.jpnprd01.prod.outlook.com>
Date:   Mon, 12 Sep 2022 07:58:31 +0000
From:   "matsuda-daisuke@...itsu.com" <matsuda-daisuke@...itsu.com>
To:     'Bart Van Assche' <bvanassche@....org>,
        Yanjun Zhu <yanjun.zhu@...ux.dev>,
        "linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>,
        "leonro@...dia.com" <leonro@...dia.com>,
        "jgg@...dia.com" <jgg@...dia.com>,
        "zyjzyj2000@...il.com" <zyjzyj2000@...il.com>
CC:     "nvdimm@...ts.linux.dev" <nvdimm@...ts.linux.dev>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "rpearsonhpe@...il.com" <rpearsonhpe@...il.com>,
        "yangx.jy@...itsu.com" <yangx.jy@...itsu.com>,
        "lizhijian@...itsu.com" <lizhijian@...itsu.com>,
        "y-goto@...itsu.com" <y-goto@...itsu.com>
Subject: RE: [RFC PATCH 2/7] RDMA/rxe: Convert the triple tasklets to
 workqueues

On Mon, Sep 12, 2022 12:09 AM Bart Van Assche wrote:
> On 9/11/22 00:10, Yanjun Zhu wrote:
> > I also implemented a workqueue for rxe. IMO, can we add a variable to
> > decide to use tasklet or workqueue?
> >
> > If user prefer using tasklet, he can set the variable to use
> > tasklet. And the default is tasklet. Set the variable to another
> > value to use workqueue.

That's an interesting idea, but I am not sure how users specify it.
IIRC, tasklets are generated when rdma link is added, typically by 
executing ' rdma link add' command. I don't think we can add
an device specific option to the utility(iproute2/rdma).

> 
> I'm in favor of removing all uses of the tasklet mechanism because of
> the disadvantages of that mechanism. See also:
> * "Eliminating tasklets" (https://lwn.net/Articles/239633/).
> * "Modernizing the tasklet API" (https://lwn.net/Articles/830964/).
> * Sebastian Andrzej Siewior's opinion about tasklets
> (https://lore.kernel.org/all/YvovfXMJQAUBsvBZ@linutronix.de/).

I am also in favor of using workqueues alone not only because of the
disadvantages above but also to avoid complexity. I would like to know
if there is anybody who will bothered by the change especially in terms
of performance.

Thanks,
Daisuke

> 
> Thanks,
> 
> Bart.