linux-ext4 - Re: how to disable readahead

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Message-ID: <8a519c07-8c87-33c1-944a-5c7636c061d6@thelounge.net>
Date:   Thu, 2 Aug 2018 18:01:22 +0200
From:   Reindl Harald <h.reindl@...lounge.net>
To:     "Bean Huo (beanhuo)" <beanhuo@...ron.com>,
        Jack Wang <jack.wang.usish@...il.com>
Cc:     "tytso@....edu" <tytso@....edu>,
        "linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
        "beanhuo.linux@...gle.com" <beanhuo.linux@...gle.com>
Subject: Re: how to disable readahead



Am 02.08.2018 um 17:57 schrieb Bean Huo (beanhuo):
>>>> I guess you're doing buffered IO, have you try to use direct IO?
>>>>
>>> Direct I/O is another case, it is true that will bypass readahead.
>>> But I want to disable readahead with page cache.
>>
>> don't get me wrong but when you state "I am newbie on ext4" this all sounds
>> like "having solution, seeking for problem"
> 
> No solution, I only want to disable ext4 readahead with keeping page cache.
> I am curious about that flash based SDD/UFS/eMMC already has readahead in the FW, what is benefit of readahead in the FS under this condition?

you still miss to point out the *problem* you are trying to solve and "i
want" is no reasoning - as newbie you really should trust the developers
that they know what they are doing and not play around with something
for no good reason