* File-compression on ubifs
@ 2019-05-17 11:36 Shibin George
2019-06-04 15:14 ` Shibin George
2019-06-04 21:04 ` Richard Weinberger
0 siblings, 2 replies; 3+ messages in thread
From: Shibin George @ 2019-05-17 11:36 UTC (permalink / raw)
To: linux-mtd
Hi everyone,
Had a query regarding mkfs.ubifs tool. I created an empty ubifs
filesystem using:
mkfs.ubifs -y /dev/ubiX_Y
I was wondering that if I now create a new file on this filesystem
(after mount()), would compression be enabled or disabled for that
file by-default? I am sorry but I could quite grasp this from the
mkfs.ubifs code.
Another query that I have is this:
Would ubifs do a better job at compression if it knows the root-dir
contents ahead of time? In other words, is on-the-fly compression of a
file (i.e. compression at the time of creating/writing to a file)
generally worse than when the same file is known to ubifs at the time
of image creation?
Thanks for your time!
Regards,
Shibin George
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: File-compression on ubifs
2019-05-17 11:36 File-compression on ubifs Shibin George
@ 2019-06-04 15:14 ` Shibin George
2019-06-04 21:04 ` Richard Weinberger
1 sibling, 0 replies; 3+ messages in thread
From: Shibin George @ 2019-06-04 15:14 UTC (permalink / raw)
To: linux-mtd
Any pointers would be appreciated, Thanks again!
Regards,
Shibin George
On Fri, May 17, 2019 at 5:06 PM Shibin George
<george.shibin1993@gmail.com> wrote:
>
> Hi everyone,
>
> Had a query regarding mkfs.ubifs tool. I created an empty ubifs
> filesystem using:
>
> mkfs.ubifs -y /dev/ubiX_Y
>
> I was wondering that if I now create a new file on this filesystem
> (after mount()), would compression be enabled or disabled for that
> file by-default? I am sorry but I could quite grasp this from the
> mkfs.ubifs code.
>
> Another query that I have is this:
> Would ubifs do a better job at compression if it knows the root-dir
> contents ahead of time? In other words, is on-the-fly compression of a
> file (i.e. compression at the time of creating/writing to a file)
> generally worse than when the same file is known to ubifs at the time
> of image creation?
>
> Thanks for your time!
>
> Regards,
> Shibin George
______________________________________________________
Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: File-compression on ubifs
2019-05-17 11:36 File-compression on ubifs Shibin George
2019-06-04 15:14 ` Shibin George
@ 2019-06-04 21:04 ` Richard Weinberger
1 sibling, 0 replies; 3+ messages in thread
From: Richard Weinberger @ 2019-06-04 21:04 UTC (permalink / raw)
To: Shibin George; +Cc: linux-mtd
On Fri, May 17, 2019 at 1:37 PM Shibin George
<george.shibin1993@gmail.com> wrote:
>
> Hi everyone,
>
> Had a query regarding mkfs.ubifs tool. I created an empty ubifs
> filesystem using:
>
> mkfs.ubifs -y /dev/ubiX_Y
No need to run mkfs.ubifs, just mount an empty ubi volume as ubifs, it
will auto create
a filesystem for you.
> I was wondering that if I now create a new file on this filesystem
> (after mount()), would compression be enabled or disabled for that
> file by-default? I am sorry but I could quite grasp this from the
> mkfs.ubifs code.
Compression is enabled by default, unless the filesystem is encrypted.
You can also override the default compressor using the compr= mount-option.
> Another query that I have is this:
> Would ubifs do a better job at compression if it knows the root-dir
> contents ahead of time? In other words, is on-the-fly compression of a
> file (i.e. compression at the time of creating/writing to a file)
> generally worse than when the same file is known to ubifs at the time
> of image creation?
UBIFS compression works on 4k chunks, it should not matter whether you compress
at runtime or at mkfs.ubifs time.
If you're looking for better compression rates, give our zstd patches a try.
You can find them on the mailinglist.
--
Thanks,
//richard
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2019-06-04 15:14 ` Shibin George
2019-06-04 21:04 ` Richard Weinberger
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