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Date:   Wed, 26 Jul 2023 20:20:44 +0530
From:   Ojaswin Mujoo <ojaswin@linux.ibm.com>
To:     Kemeng Shi <shikemeng@huaweicloud.com>
Cc:     tytso@mit.edu, adilger.kernel@dilger.ca, ritesh.list@gmail.com,
        linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 10/10] ext4: correct some stale comment of criteria
Message-ID: <ZMEyxLauFkXBwgUZ@li-bb2b2a4c-3307-11b2-a85c-8fa5c3a69313.ibm.com>
References: <20230725185106.2147273-1-shikemeng@huaweicloud.com>
 <20230725185106.2147273-11-shikemeng@huaweicloud.com>
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On Wed, Jul 26, 2023 at 02:51:06AM +0800, Kemeng Shi wrote:
> We named criteria with CR_XXX, correct stale comment to criteria with
> raw number.

Hi Kemeng,

Thanks for the cleanups.

> 
> Fixes: f52f3d2b9fba ("ext4: Give symbolic names to mballoc criterias")
> Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
> Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
> ---
>  fs/ext4/mballoc.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index 36eea63eaace..de5da76e6748 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -2777,8 +2777,8 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac)
>  
>  	/*
>  	 * ac->ac_2order is set only if the fe_len is a power of 2
> -	 * if ac->ac_2order is set we also set criteria to 0 so that we
> -	 * try exact allocation using buddy.
> +	 * if ac->ac_2order is set we also set criteria to CR_POWER2_ALIGNED
> +	 * so that we try exact allocation using buddy.
>  	 */
>  	i = fls(ac->ac_g_ex.fe_len);
>  	ac->ac_2order = 0;
> @@ -2835,8 +2835,8 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac)
>  			/*
>  			 * Batch reads of the block allocation bitmaps
>  			 * to get multiple READs in flight; limit
> -			 * prefetching at cr=0/1, otherwise mballoc can
> -			 * spend a lot of time loading imperfect groups
> +			 * prefetching at cr below CR_FAST, otherwise mballoc

One of my earlier patchset has replaced the CR_FAST macro with
ext4_mb_cr_expensive() so maybe we can account for that here:

https://lore.kernel.org/linux-ext4/20230630085927.140137-1-ojaswin@linux.ibm.com/

Regards,
ojaswin

> +			 * can spend a lot of time loading imperfect groups

>  			 */
>  			if ((prefetch_grp == group) &&
>  			    (cr >= CR_FAST ||
> -- 
> 2.30.0
>