From: Christoph Hellwig <hch@infradead.org>
To: "Isaac J. Manjarres" <isaacm@codeaurora.org>
Cc: pratikp@codeaurora.org, linux-kernel@vger.kernel.org,
Liam Mark <lmark@codeaurora.org>,
iommu@lists.linux-foundation.org, kernel-team@android.com
Subject: Re: [RFC PATCH] iommu/iova: Add a best-fit algorithm
Date: Mon, 17 Feb 2020 00:03:39 -0800 [thread overview]
Message-ID: <20200217080339.GC10342@infradead.org> (raw)
In-Reply-To: <1581721602-17010-1-git-send-email-isaacm@codeaurora.org>
On Fri, Feb 14, 2020 at 03:06:42PM -0800, Isaac J. Manjarres wrote:
> From: Liam Mark <lmark@codeaurora.org>
>
> Using the best-fit algorithm, instead of the first-fit
> algorithm, may reduce fragmentation when allocating
> IOVAs.
As we like to say in standards groups: may also implies may not.
Please provide numbers showing that this helps, and preferably and
explanation how it doesn't hurt as well.
> + * Should be called prior to using dma-apis.
> + */
> +int iommu_dma_enable_best_fit_algo(struct device *dev)
> +{
> + struct iommu_domain *domain;
> + struct iova_domain *iovad;
> +
> + domain = iommu_get_domain_for_dev(dev);
> + if (!domain || !domain->iova_cookie)
> + return -EINVAL;
>
> + iovad = &((struct iommu_dma_cookie *)domain->iova_cookie)->iovad;
> + iovad->best_fit = true;
> return 0;
> }
> +EXPORT_SYMBOL(iommu_dma_enable_best_fit_algo);
Who is going to call this? Patches adding exports always need a user
that goes along with the export. Also drivers have no business calling
directly into dma-iommu.
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WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@infradead.org>
To: "Isaac J. Manjarres" <isaacm@codeaurora.org>
Cc: iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
Liam Mark <lmark@codeaurora.org>,
joro@8bytes.org, pratikp@codeaurora.org, kernel-team@android.com
Subject: Re: [RFC PATCH] iommu/iova: Add a best-fit algorithm
Date: Mon, 17 Feb 2020 00:03:39 -0800 [thread overview]
Message-ID: <20200217080339.GC10342@infradead.org> (raw)
In-Reply-To: <1581721602-17010-1-git-send-email-isaacm@codeaurora.org>
On Fri, Feb 14, 2020 at 03:06:42PM -0800, Isaac J. Manjarres wrote:
> From: Liam Mark <lmark@codeaurora.org>
>
> Using the best-fit algorithm, instead of the first-fit
> algorithm, may reduce fragmentation when allocating
> IOVAs.
As we like to say in standards groups: may also implies may not.
Please provide numbers showing that this helps, and preferably and
explanation how it doesn't hurt as well.
> + * Should be called prior to using dma-apis.
> + */
> +int iommu_dma_enable_best_fit_algo(struct device *dev)
> +{
> + struct iommu_domain *domain;
> + struct iova_domain *iovad;
> +
> + domain = iommu_get_domain_for_dev(dev);
> + if (!domain || !domain->iova_cookie)
> + return -EINVAL;
>
> + iovad = &((struct iommu_dma_cookie *)domain->iova_cookie)->iovad;
> + iovad->best_fit = true;
> return 0;
> }
> +EXPORT_SYMBOL(iommu_dma_enable_best_fit_algo);
Who is going to call this? Patches adding exports always need a user
that goes along with the export. Also drivers have no business calling
directly into dma-iommu.
next prev parent reply other threads:[~2020-02-17 8:03 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-14 23:06 [RFC PATCH] iommu/iova: Add a best-fit algorithm Isaac J. Manjarres
2020-02-14 23:06 ` Isaac J. Manjarres
2020-02-17 8:03 ` Christoph Hellwig [this message]
2020-02-17 8:03 ` Christoph Hellwig
2020-02-17 16:03 ` Robin Murphy
2020-02-17 16:03 ` Robin Murphy
2020-02-19 12:28 ` Will Deacon
2020-02-19 12:28 ` Will Deacon
2020-02-20 6:38 ` isaacm
2020-02-20 6:38 ` isaacm
2020-02-20 18:42 ` Robin Murphy
2020-02-20 18:42 ` Robin Murphy
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