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From: David Miller <>
Subject: Re: [Linux-kernel-mentees] [PATCH 0/2] reorder members of structures in virtio_net for optimization
Date: Fri, 02 Oct 2020 19:06:38 -0700 (PDT)	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

From: Anant Thazhemadam <>
Date: Wed, 30 Sep 2020 10:47:20 +0530

> The structures virtnet_info and receive_queue have byte holes in 
> middle, and their members could do with some rearranging 
> (order-of-declaration wise) in order to overcome this.
> Rearranging the members helps in:
>   * elimination the byte holes in the middle of the structures
>   * reduce the size of the structure (virtnet_info)
>   * have more members stored in one cache line (as opposed to 
>     unnecessarily crossing the cacheline boundary and spanning
>     different cachelines)
> The analysis was performed using pahole.
> These patches may be applied in any order.

What effects do these changes have on performance?

The cache locality for various TX and RX paths could be effected.

I'm not applying these patches without some data on the performance

Thank you.

Linux-kernel-mentees mailing list

  parent reply	other threads:[~2020-10-03  2:06 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-30  5:17 [Linux-kernel-mentees] [PATCH 0/2] reorder members of structures in virtio_net for optimization Anant Thazhemadam
2020-09-30  5:17 ` [Linux-kernel-mentees] [PATCH 1/2] net: reorder members of virtnet_info " Anant Thazhemadam
2020-09-30  5:17 ` [Linux-kernel-mentees] [PATCH 2/2] net: reorder members of receive_queue in virtio_net " Anant Thazhemadam
2020-10-03  2:06 ` David Miller [this message]
2020-10-03 18:43   ` [Linux-kernel-mentees] [PATCH 0/2] reorder members of structures " Michael S. Tsirkin

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