From: Minchan Kim <minchan@kernel.org>
To: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Luigi Semenzato <semenzato@google.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Jens Axboe <axboe@kernel.dk>,
Seth Jennings <sjenning@linux.vnet.ibm.com>,
Nitin Gupta <ngupta@vflare.org>,
Konrad Rzeszutek Wilk <konrad@darnok.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Pekka Enberg <penberg@cs.helsinki.fi>,
Mel Gorman <mgorman@suse.de>
Subject: Re: [PATCH v6 0/5] zram/zsmalloc promotion
Date: Fri, 16 Aug 2013 13:35:56 +0900 [thread overview]
Message-ID: <20130816043556.GA6216@gmail.com> (raw)
In-Reply-To: <520d883a.a2f6420a.6f36.0d66SMTPIN_ADDED_BROKEN@mx.google.com>
Hi,
On Fri, Aug 16, 2013 at 10:02:08AM +0800, Wanpeng Li wrote:
> Hi Minchan,
> On Thu, Aug 15, 2013 at 01:17:53AM +0900, Minchan Kim wrote:
> >Hi Luigi,
> >
> >On Wed, Aug 14, 2013 at 08:53:31AM -0700, Luigi Semenzato wrote:
> >> During earlier discussions of zswap there was a plan to make it work
> >> with zsmalloc as an option instead of zbud. Does zbud work for
> >
> >AFAIR, it was not an optoin but zsmalloc was must but there were
> >several objections because zswap's notable feature is to dump
> >compressed object to real swap storage. For that, zswap needs to
> >store bounded objects in a zpage so that dumping could be bounded, too.
> >Otherwise, it could encounter OOM easily.
> >
> >> compression factors better than 2:1? I have the impression (maybe
> >> wrong) that it does not. In our use of zram (Chrome OS) typical
> >
> >Since zswap changed allocator from zsmalloc to zbud, I didn't follow
> >because I had no interest of low compressoin ratio allocator so
> >I have no idea of status of zswap at a moment but I guess it would be
> >still 2:1.
> >
> >> overall compression ratios are between 2.5:1 and 3:1. We would hate
> >> to waste that memory if we switch to zswap.
> >
> >If you have real swap storage, zswap might be better although I have
> >no number but real swap is money for embedded system and it has sudden
> >garbage collection on firmware side if we use eMMC or SSD so that it
> >could affect system latency. Morever, if we start to use real swap,
> >maybe we should encrypt the data and it would be severe overhead(CPU
> >and Power).
> >
>
> Why real swap for embedded system need encrypt the data? I think there
> is no encrypt for data against server and desktop.
I have used some portable device but suddenly, I lost it or was stolen.
A hacker can pick it up and read my swap and found my precious information.
I don't want it. I guess it's one of reason ChromeOS don't want to use real
swap.
https://groups.google.com/a/chromium.org/forum/#!msg/chromium-os-discuss/92Fvi4Ezego/ZvbrC3L2FG4J
>
> >And what I am considering after promoting for zram feature is
> >asynchronous I/O and it's possible because zram is block device.
> >
> >Thanks!
> >--
> >Kind regards,
> >Minchan Kim
> >
> >--
> >To unsubscribe, send a message with 'unsubscribe linux-mm' in
> >the body to majordomo@kvack.org. For more info on Linux MM,
> >see: http://www.linux-mm.org/ .
> >Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
>
--
Kind regards,
Minchan Kim
next prev parent reply other threads:[~2013-08-16 4:36 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-14 5:55 [PATCH v6 0/5] zram/zsmalloc promotion Minchan Kim
2013-08-14 5:55 ` [PATCH v6 1/5] zsmalloc: add Kconfig for enabling page table method Minchan Kim
2013-08-14 5:55 ` [PATCH v6 2/5] zsmalloc: add more comment Minchan Kim
2013-08-14 5:55 ` [PATCH v6 3/5] zsmalloc: move it under zram Minchan Kim
2013-08-16 22:00 ` Seth Jennings
2013-08-20 4:21 ` Minchan Kim
2013-08-14 5:55 ` [PATCH v6 4/5] mm: export unmap_kernel_range Minchan Kim
2013-08-14 5:55 ` [PATCH v6 5/5] zram: promote zram from staging Minchan Kim
2013-08-14 15:53 ` [PATCH v6 0/5] zram/zsmalloc promotion Luigi Semenzato
2013-08-14 16:17 ` Minchan Kim
2013-08-15 0:18 ` Bob Liu
[not found] ` <520d883a.a2f6420a.6f36.0d66SMTPIN_ADDED_BROKEN@mx.google.com>
2013-08-16 4:35 ` Minchan Kim [this message]
2013-08-14 17:40 ` Mel Gorman
2013-08-14 18:15 ` Luigi Semenzato
2013-08-14 18:58 ` Minchan Kim
2013-08-15 17:12 ` Mel Gorman
2013-08-16 1:52 ` Bob Liu
2013-08-16 1:53 ` Bob Liu
2013-08-16 4:26 ` Minchan Kim
2013-08-16 4:55 ` Bob Liu
2013-08-16 8:33 ` Mel Gorman
2013-08-16 9:12 ` Mel Gorman
2013-08-16 9:18 ` Bob Liu
2013-08-16 12:49 ` Greg Kroah-Hartman
2013-08-16 9:12 ` Bob Liu
2013-08-19 3:18 ` Minchan Kim
2013-08-19 3:57 ` Bob Liu
2013-08-19 4:37 ` Minchan Kim
2013-08-19 5:29 ` Luigi Semenzato
2013-08-19 6:07 ` Bob Liu
2013-08-19 6:11 ` Minchan Kim
-- strict thread matches above, loose matches on Subject: below --
2013-08-14 5:51 Minchan Kim
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20130816043556.GA6216@gmail.com \
--to=minchan@kernel.org \
--cc=akpm@linux-foundation.org \
--cc=axboe@kernel.dk \
--cc=gregkh@linuxfoundation.org \
--cc=konrad@darnok.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=liwanp@linux.vnet.ibm.com \
--cc=mgorman@suse.de \
--cc=ngupta@vflare.org \
--cc=penberg@cs.helsinki.fi \
--cc=semenzato@google.com \
--cc=sjenning@linux.vnet.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).