netdev - Re: [PATCH net-next v15 08/15] net: homa: create homa_pacer.h and homa

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Message-ID: <CAGXJAmz50OiZM65sB43k5Gh34nZ6TAx7_1Bx0XDPrpJ-uWUj4w@mail.gmail.com>
Date: Mon, 1 Sep 2025 09:35:04 -0700
From: John Ousterhout <ouster@...stanford.edu>
To: Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, edumazet@...gle.com, horms@...nel.org, 
	kuba@...nel.org
Subject: Re: [PATCH net-next v15 08/15] net: homa: create homa_pacer.h and homa_pacer.c

On Tue, Aug 26, 2025 at 3:54 AM Paolo Abeni <pabeni@...hat.com> wrote:
>
> On 8/18/25 10:55 PM, John Ousterhout wrote:
> > +/**
> > + * homa_pacer_alloc() - Allocate and initialize a new pacer object, which
> > + * will hold pacer-related information for @homa.
> > + * @homa:   Homa transport that the pacer will be associated with.
> > + * Return:  A pointer to the new struct pacer, or a negative errno.
> > + */
> > +struct homa_pacer *homa_pacer_alloc(struct homa *homa)
> > +{
> > +     struct homa_pacer *pacer;
> > +     int err;
> > +
> > +     pacer = kzalloc(sizeof(*pacer), GFP_KERNEL);
> > +     if (!pacer)
> > +             return ERR_PTR(-ENOMEM);
> > +     pacer->homa = homa;
> > +     spin_lock_init(&pacer->mutex);
> > +     pacer->fifo_count = 1000;
> > +     spin_lock_init(&pacer->throttle_lock);
> > +     INIT_LIST_HEAD_RCU(&pacer->throttled_rpcs);
> > +     pacer->fifo_fraction = 50;
> > +     pacer->max_nic_queue_ns = 5000;
> > +     pacer->throttle_min_bytes = 1000;
> > +     init_waitqueue_head(&pacer->wait_queue);
> > +     pacer->kthread = kthread_run(homa_pacer_main, pacer, "homa_pacer");
> > +     if (IS_ERR(pacer->kthread)) {
> > +             err = PTR_ERR(pacer->kthread);
> > +             pr_err("Homa couldn't create pacer thread: error %d\n", err);
> > +             goto error;
> > +     }
> > +     atomic64_set(&pacer->link_idle_time, homa_clock());
> > +
> > +     homa_pacer_update_sysctl_deps(pacer);
>
> IMHO this does not fit mergeable status:
> - the static init (@25Gbs)
> - never updated on link changes
> - assumes a single link in the whole system
>
> I think it's better to split the pacer part out of this series, or the
> above points should be addressed and it would be difficult fitting a
> reasonable series size.

I have removed the pacer from the patch series.

-John-