Re: [PATCH V2 2/3] drivers/staging: zcache: host services and PAM services

On 02/09/2011 06:46 PM, Minchan Kim wrote:

Hi Nitin,

Sorry for late response.

On Thu, Feb 10, 2011 at 2:36 AM, Nitin Gupta[off-list ref]  wrote:

quoted

On 02/09/2011 11:39 AM, Dan Magenheimer wrote:

quoted

quoted

From: Minchan Kim [mailto:minchan.kim@gmail.com]

quoted

As I read your comment, I can't find the benefit of zram compared to
frontswap.

Well, I am biased, but I agree that frontswap is a better technical
solution than zram. ;-)  But "dynamic-ity" is very important to
me and may be less important to others.

I agree that frontswap is better than zram when considering swap as the use
case - no bio overhead, dynamic resizing. However, zram being a *generic*
block-device has some unique cases too like hosting files on /tmp, various
caches under /var or any place where a compressed in-memory block device can
help.

Yes. I mentioned that benefit but I am not sure the reason is enough.
What I had in mind long time ago is that zram's functionality into brd.
So someone who want to compress contents could use it with some mount
option to enable compression.
By such way, many ramdisk user can turn it on easily.
If many user begin using the brd, we can see many report about
performance then solve brd performance s as well as zcache world-wide
usage.

Hmm,  the idea is too late?

quoted

So, frontswap and zram have overlapping use case of swap but are not the
same.

If we can insert zram's functionality into brd, maybe there is no
reason to coexist.

quoted

I thought about this before starting with zram development but thought 
adding compression (and in future, defrag) and use of custom allocator 
is just too much of a hassle and thus dropped the idea. If someone is 
anyhow interested in merging brd and zram I would be glad to help but I 
still think that is simply not worth the effort.

Thanks,
Nitin

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