Re: 2 minutes for a reiser4 filesystem to mount.

[Georgios Tsalikis <georgios@tsalikis.net>]

On 25/10/2015 01:39 πμ, Ivan Shapovalov wrote:
> On 2015-10-24 at 22:41 +0300, Georgios Tsalikis wrote:
>> On 24/10/2015 01:58 πμ, Ivan Shapovalov wrote:
>>>> 24 окт. 2015 г., в 1:06, Georgios Tsalikis <georgios.tsalikis@hol
>>>> .gr> написал(а):
>>>>
>>>>> On 24/10/2015 12:37 πμ, Ivan Shapovalov wrote:
>>>>>> On 2015-10-22 at 20:38 +0300, Georgios Tsalikis wrote:
>>>>>> The filesystem is 1.7GB large, lies in a GPT patition and is
>>>>>> formated
>>>>>> with -o node=node41 without any other override. The kernel is
>>>>>> 4.2.3
>>>>>> with
>>>>>> the 4.2.2 patch.
>>>>>> I tried the same on a 250MB partition and it mounts
>>>>>> instantly. dmesg
>>>>>> shows nothing special
>>>>>> Any ideas? Thanks in advance. :)
>>>>> Hello,
>>>>>
>>>>> try "dont_load_bitmap" in mount options. However, this is
>>>>> anyway very
>>>>> strange for a ~2GB partition...
>>>> I am sorry, did i write 1.7GB? I meant 1.7TB... i am old and such
>>>> figures dont fit my mind easily!
>>> Ah, so it's 1.7 TB? Then it's not unusual at all. Indeed, try
>>> mounting with `-o dont_load_bitmap`.
>>>
>> I did so and it worked. Thank you. But what does that option do?
> This option tells reiser4 to load bitmap blocks on demand, and not all
> at once at filesystem mount time.
Does this mean using this option means a penalty? Maybe in some cases 
(servers etc) it is worth waiting the fs to mount?
>
> The bitmap is how reiser4 stores information about which on-disk blocks
> are allocated and which are free (one bit corresponds to one block,
> hence the name).
>
> The 2TiB filesystem has 2*1024^4 / 4096 = 536870912 blocks, which take
> 536870912 / (8*4096) = 16384 bitmap blocks, so it takes 120/16384 ~ 7ms
> to load one block, which is not that unusual (given that the bitmap
> loading doesn't seem to be optimized too well: each block is read in a
> separate request).
>
>> And which are the other options and their function?
> I'm afraid that the full list of reiser4 options can only be found in
> code (file init_super.c, functions push_sb_field_opts() and
> reiser4_init_super_data().
>

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