Re: Do I have to do anything to make sure ext4lazyinit works as being advertised ?
On Wed, Feb 01, 2017 at 04:53:34AM +0530, shirish शिरीष wrote:
> hmm.... From what little I understand, it always the slowest interface
> that needs to be supported.
> And IIUC , in ext4lazyinit's case it is probably some of the MMC cards
> due to which the 16 MB/S transmission is kept - although some of them
> are at 104 MB/S as well.
> Whereas USB are at -
> USB 2.0 - 35 MB/S
> USB 3.0 - 400 MB/S
> USB 3.1 - Gen 1 - 400 MB/S
> USB 3.2 - Gen 2 - 1280 MB/S
> For HDD -
> SATA 1 - starts at 150 MB/S
Well they wanted to keep the rate low enough that you could still use the
disk while it was doing the background init work. Most disks can do more
than 16MB/s so that leaves some for other use, like doing your install.
> Another query - if instead ext4lazyinit IF -
> mkfs.ext4 -E lazy_itable_init=0,lazy_journal_init=0 /dev/mapper/fc-root
> is applied then would it would start formatting and making inodes at a
> much faster rate - i.e. slowest between the USB Drive and HDD in a
> typical workstation - which probably would be a jump 3-4 times the
> speed that ext4lazyinit would employ.
Well it would have to do the whole init up front, meaning you have to
wait for all of it to finish before doing the install.
> WDYT ?
> If yes, how as a user could I apply/use the above command while using
> debian-installer ?
Not sure. It has been a while since I poked at the installer code.
I don't think it's worth trying to poke at it. I think the default
behavour sounce very sensible and I doubt for most use cases doing it
differently would be an improvement, most like it would make it worse.