linux-kernel - Re: [PATCH v3 12/13] mm: Add sysctl vm.compress-batching switch for compress batching during swapout.

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Message-Id: <20241106121754.644440c6d8d1edf60f6163d7@linux-foundation.org>
Date: Wed, 6 Nov 2024 12:17:54 -0800
From: Andrew Morton <akpm@...ux-foundation.org>
To: Kanchana P Sridhar <kanchana.p.sridhar@...el.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org, hannes@...xchg.org,
 yosryahmed@...gle.com, nphamcs@...il.com, chengming.zhou@...ux.dev,
 usamaarif642@...il.com, ryan.roberts@....com, ying.huang@...el.com,
 21cnbao@...il.com, linux-crypto@...r.kernel.org,
 herbert@...dor.apana.org.au, davem@...emloft.net, clabbe@...libre.com,
 ardb@...nel.org, ebiggers@...gle.com, surenb@...gle.com,
 kristen.c.accardi@...el.com, zanussi@...nel.org, wajdi.k.feghali@...el.com,
 vinodh.gopal@...el.com
Subject: Re: [PATCH v3 12/13] mm: Add sysctl vm.compress-batching switch for
 compress batching during swapout.

On Wed,  6 Nov 2024 11:21:04 -0800 Kanchana P Sridhar <kanchana.p.sridhar@...el.com> wrote:

>  extern int sysctl_legacy_va_layout;
> +extern unsigned int compress_batching;

nit: I suggest calling this "sysctl_compress_batching".  See how we
treated sysctl_legacy_va_layout.

> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -47,6 +47,9 @@
>  int page_cluster;
>  const int page_cluster_max = 31;
>  
> +/* Enable/disable compress batching during swapout. */
> +unsigned int compress_batching;
> +
>  struct cpu_fbatches {
>  	/*
>  	 * The following folio batches are grouped together because they are protected
> @@ -1074,4 +1077,7 @@ void __init swap_setup(void)
>  	 * Right now other parts of the system means that we
>  	 * _really_ don't want to cluster much more
>  	 */
> +
> +	/* Disable compress batching during swapout by default. */
> +	compress_batching = 0;

Not really needed?  The compiler already did that.

>  }