From: Saeed Mahameed <saeed@kernel.org>
To: Jakub Kicinski <kuba@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>,
netdev@vger.kernel.org, Eran Ben Elisha <eranbe@nvidia.com>,
Moshe Shemesh <moshe@nvidia.com>
Subject: Re: [net V2 05/15] net/mlx5: Add retry mechanism to the command entry index allocation
Date: Fri, 02 Oct 2020 10:03:14 -0700 [thread overview]
Message-ID: <cda8be83538b9cac786b12ea8324248e88f62be1.camel@kernel.org> (raw)
In-Reply-To: <20201001162336.45f552b3@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
On Thu, 2020-10-01 at 16:23 -0700, Jakub Kicinski wrote:
> On Thu, 1 Oct 2020 12:52:37 -0700 saeed@kernel.org wrote:
> > +static int cmd_alloc_index_retry(struct mlx5_cmd *cmd)
> > +{
> > + unsigned long alloc_end = jiffies + msecs_to_jiffies(1000);
> > + int idx;
> > +
> > +retry:
> > + idx = cmd_alloc_index(cmd);
> > + if (idx < 0 && time_before(jiffies, alloc_end)) {
> > + /* Index allocation can fail on heavy load of commands.
> > This is a temporary
> > + * situation as the current command already holds the
> > semaphore, meaning that
> > + * another command completion is being handled and it
> > is expected to release
> > + * the entry index soon.
> > + */
> > + cond_resched();
> > + goto retry;
> > + }
> > + return idx;
> > +}
>
> This looks excessive. At least add some cpu_relax(), or udelay()?
cpu_relax() should also work fine, it is just that we have 100%
certainty that the allocation will success real soon.
next prev parent reply other threads:[~2020-10-02 17:03 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-01 19:52 [pull request][net V2 00/15] mlx5 fixes 2020-09-30 saeed
2020-10-01 19:52 ` [net V2 01/15] net/mlx5: Don't allow health work when device is uninitialized saeed
2020-10-01 23:15 ` Jakub Kicinski
2020-10-02 16:57 ` Saeed Mahameed
2020-10-01 19:52 ` [net V2 02/15] net/mlx5: Fix a race when moving command interface to polling mode saeed
2020-10-01 19:52 ` [net V2 03/15] net/mlx5: Avoid possible free of command entry while timeout comp handler saeed
2020-10-01 19:52 ` [net V2 04/15] net/mlx5: poll cmd EQ in case of command timeout saeed
2020-10-01 19:52 ` [net V2 05/15] net/mlx5: Add retry mechanism to the command entry index allocation saeed
2020-10-01 23:23 ` Jakub Kicinski
2020-10-02 17:03 ` Saeed Mahameed [this message]
2020-10-01 19:52 ` [net V2 06/15] net/mlx5: cmdif, Avoid skipping reclaim pages if FW is not accessible saeed
2020-10-01 19:52 ` [net V2 07/15] net/mlx5: Fix request_irqs error flow saeed
2020-10-01 23:24 ` Jakub Kicinski
2020-10-02 17:05 ` Saeed Mahameed
2020-10-02 17:19 ` Mark Bloch
2020-10-02 17:27 ` Saeed Mahameed
2020-10-01 19:52 ` [net V2 08/15] net/mlx5e: Fix error path for RQ alloc saeed
2020-10-01 19:52 ` [net V2 09/15] net/mlx5e: Add resiliency in Striding RQ mode for packets larger than MTU saeed
2020-10-01 23:27 ` Jakub Kicinski
2020-10-02 17:06 ` Saeed Mahameed
2020-10-01 19:52 ` [net V2 10/15] net/mlx5e: CT, Fix coverity issue saeed
2020-10-01 19:52 ` [net V2 11/15] net/mlx5e: Fix driver's declaration to support GRE offload saeed
2020-10-01 19:52 ` [net V2 12/15] net/mlx5e: Fix return status when setting unsupported FEC mode saeed
2020-10-01 19:52 ` [net V2 13/15] net/mlx5e: Fix VLAN cleanup flow saeed
2020-10-01 19:52 ` [net V2 14/15] net/mlx5e: Fix VLAN create flow saeed
2020-10-01 19:52 ` [net V2 15/15] net/mlx5e: Fix race condition on nhe->n pointer in neigh update saeed
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