linux-kernel - Re: [PATCH] RDMA/core: reduce IB_POLL

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Message-ID: <d2875648-20d9-43b9-abf1-8ecbf049c4bf@wdc.com>
Date:   Tue, 27 Feb 2018 16:21:05 -0800
From:   Bart Van Assche <bart.vanassche@....com>
To:     Max Gurtovoy <maxg@...lanox.com>, Jason Gunthorpe <jgg@...pe.ca>,
        Sagi Grimberg <sagi@...mberg.me>
Cc:     Chuck Lever <chuck.lever@...cle.com>,
        "arnd@...db.de" <arnd@...db.de>,
        "dledford@...hat.com" <dledford@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "leonro@...lanox.com" <leonro@...lanox.com>,
        "linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>
Subject: Re: [PATCH] RDMA/core: reduce IB_POLL_BATCH constant

On 02/27/18 14:15, Max Gurtovoy wrote:
> -static int __ib_process_cq(struct ib_cq *cq, int budget, struct ib_wc 
> *poll_wc)
> +static int __ib_process_cq(struct ib_cq *cq, int budget, struct ib_wc 
> *poll_wc,
> +                          int batch)
>   {
> -       int i, n, completed = 0;
> -       struct ib_wc *wcs = poll_wc ? : cq->wc;
> +       int i, n, ib_poll_batch, completed = 0;
> +       struct ib_wc *wcs;
> +
> +       if (poll_wc) {
> +               wcs = poll_wc;
> +               ib_poll_batch = batch;
> +       } else {
> +               wcs = cq->wc;
> +               ib_poll_batch = IB_POLL_BATCH;
> +       }

Since this code has to be touched I think that we can use this 
opportunity to get rid of the "poll_wc ? : cq->wc" conditional and 
instead use what the caller passes. That will require to update all 
__ib_process_cq(..., ..., NULL) calls. I also propose to let the caller 
pass ib_poll_batch instead of figuring it out in this function. 
Otherwise the approach of this patch looks fine to me.

Thanks,

Bart.