Re: [PATCH v3 01/14] fs: Move enum rw_hint into a new header file

[Bart Van Assche <bvanassche@acm.org>]

On 10/30/23 04:11, Kanchan Joshi wrote:
> On 10/18/2023 2:17 AM, Bart Van Assche wrote:
>> +/* Block storage write lifetime hint values. */
>> +enum rw_hint {
>> +	WRITE_LIFE_NOT_SET	= 0, /* RWH_WRITE_LIFE_NOT_SET */
>> +	WRITE_LIFE_NONE		= 1, /* RWH_WRITE_LIFE_NONE */
>> +	WRITE_LIFE_SHORT	= 2, /* RWH_WRITE_LIFE_SHORT */
>> +	WRITE_LIFE_MEDIUM	= 3, /* RWH_WRITE_LIFE_MEDIUM */
>> +	WRITE_LIFE_LONG		= 4, /* RWH_WRITE_LIFE_LONG */
>> +	WRITE_LIFE_EXTREME	= 5, /* RWH_WRITE_LIFE_EXTREME */
>> +} __packed;
>> +
>> +static_assert(sizeof(enum rw_hint) == 1);
> 
> Does it make sense to do away with these, and have temperature-neutral
> names instead e.g., WRITE_LIFE_1, WRITE_LIFE_2?
> 
> With the current choice:
> - If the count goes up (beyond 5 hints), infra can scale fine but these
> names do not. Imagine ULTRA_EXTREME after EXTREME.
> - Applications or in-kernel users can specify LONG hint with data that
> actually has a SHORT lifetime. Nothing really ensures that LONG is
> really LONG.
> 
> Temperature-neutral names seem more generic/scalable and do not present
> the unnecessary need to be accurate with relative temperatures.

Thanks for having taken a look at this patch series. Jens asked for data
that shows that this patch series improves performance. Is this
something Samsung can help with?

Thanks,

Bart.