Re: [PATCH v1 2/2] zram: remove init_lock in zram_make_request

[Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>]

On (01/29/15 15:35), Minchan Kim wrote:
>
> As you told, the data was not stable.
>
yes. fread test was always slower, and the rest was mostly slower.


> Anyway, when I read down_read implementation, it's one atomic instruction.
> Hmm, it seems te be better for srcu_read_lock which does more things.
>
srcu looks havier, agree.

> But I guessed most of overhead are from [de]compression, memcpy, clear_page
> That's why I guessed we don't have measurable difference from that.
> What's the data pattern if you use iozone?

by "data pattern" you mean usage scenario? well, I usually use zram for
`make -jX', where X=[4..N]. so N concurrent read-write ops scenario.

	-ss

> I guess it's really simple pattern compressor can do fast. I used /dev/sda
> for dd write so more realistic data. Anyway, if we has 10% regression even if
> the data is simple, I never want to merge it.
> I will test it carefully and if it turns out lots regression,
> surely, I will not go with this and send the original patch again.

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