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Message-ID: <4caadff7-1df0-45cc-9d43-e616f9e4ddb3@bytedance.com>
Date: Fri, 24 Nov 2023 11:08:11 +0800
From: Qi Zheng <zhengqi.arch@...edance.com>
To: Kent Overstreet <kent.overstreet@...ux.dev>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
Andrew Morton <akpm@...ux-foundation.org>,
Qi Zheng <zhengqi.arch@...edance.com>,
Roman Gushchin <roman.gushchin@...ux.dev>,
Dave Chinner <david@...morbit.com>
Subject: Re: [PATCH 2/7] mm: shrinker: Add a .to_text() method for shrinkers
Hi Kent,
On 2023/11/24 05:24, Kent Overstreet wrote:
> On Thu, Nov 23, 2023 at 11:32:59AM +0800, Qi Zheng wrote:
>>> + void (*to_text)(struct seq_buf *, struct shrinker *);
>>
>> The "to_text" looks a little strange, how about naming it
>> "stat_objects"?
>
> The convention I've been using heavily in bcachefs is
> typename_to_text(), or type.to_text(), for debug reports. The
OK.
> consistency is nice.
However, this is inconsistent with the name style of other
shrinker callbacks. Please use the "objects" suffix. As for
bcachefs's own callback function, you can use typename_to_text()
to ensure consistency.
Thanks,
Qi
>
>>
>>> long batch; /* reclaim batch size, 0 = default */
>>> int seeks; /* seeks to recreate an obj */
>>> @@ -110,7 +114,6 @@ struct shrinker {
>>> #endif
>>> #ifdef CONFIG_SHRINKER_DEBUG
>>> int debugfs_id;
>>> - const char *name;
>>
>> The name will only be allocated memory when the CONFIG_SHRINKER_DEBUG is
>> enabled, otherwise its value is NULL. So you can't move it out and use
>> it while CONFIG_SHRINKER_DEBUG is disabled.
>
> Good catch
>
>>> +void shrinkers_to_text(struct seq_buf *out)
>>> +{
>>> + struct shrinker *shrinker;
>>> + struct shrinker_by_mem {
>>> + struct shrinker *shrinker;
>>> + unsigned long mem;
>>
>> The "mem" also looks a little strange, how about naming it
>> "freeable"?
>
> The type is just used in this one function, but sure.
>
>>
>>> + } shrinkers_by_mem[10];
>>> + int i, nr = 0;
>>> +
>>> + if (!mutex_trylock(&shrinker_mutex)) {
>>> + seq_buf_puts(out, "(couldn't take shrinker lock)");
>>> + return;
>>> + }
>>
>> We now have lockless method (RCU + refcount) to iterate shrinker_list,
>> please refer to shrink_slab().
>
> Will do!
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