Linux-mtd Archive on lore.kernel.org
 help / color / mirror / Atom feed
From: Wang Fangpeng <wangfangpeng1@huawei.com>
To: <linux-mtd@lists.infradead.org>, <richard@nod.at>, <dedekind1@gmail.com>
Subject: Question: background GC on UBIFS
Date: Thu, 31 Mar 2016 14:25:42 +0800	[thread overview]
Message-ID: <56FCC2E6.5020206@huawei.com> (raw)

Hi, folks,

We did some performance test of writing data to a ubifs volume by dd. The block
size of dd is 1MB.

When the volume has more than 20% free space, the speed of writing is about
1.4MB/s ~ 1.2MB/s.

However, when the free space is less and less, the speed decreases to about
83KB/s. We think the overhead is caused by GC, since GC tries to find a free
space and move valid data to another place to get a free block.

Although we already have a kthread to collect freeable blocks, it doesn't
touch blocks which have both valid and invalid nodes. My question is why don't
we do such consolidation/defragmentation periodicly, so that the overhead
could be decreased when there is not enough free space?

thanks.

             reply	other threads:[~2016-03-31  6:26 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-31  6:25 Wang Fangpeng [this message]
2016-03-31  8:53 ` Question: background GC on UBIFS Richard Weinberger
2016-03-31  9:50   ` Artem Bityutskiy

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=56FCC2E6.5020206@huawei.com \
    --to=wangfangpeng1@huawei.com \
    --cc=dedekind1@gmail.com \
    --cc=linux-mtd@lists.infradead.org \
    --cc=richard@nod.at \
    /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