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SubjectRe: What is in ubifs-2.6.git
Hi Artem

OneNAND can support for full block read also in sync burst
block read mode ,so why u want to limit bulk read only for 4
pages , with sync burst enable u can read max 64 pages.
so in place of max 4 pages , u can set max to 64 it will be
improve performance if sync burst mode is upported.

Rgs
Amit
----- Original Message -----
From: "Artem Bityutskiy" <dedekind@infradead.org>
To: <linux-fsdevel@vger.kernel.org>
Cc: <linux-mtd@lists.infradead.org>; "Adrian Hunter"
<ext-adrian.hunter@nokia.com>;
<linux-kernel@vger.kernel.org>
Sent: Tuesday, September 30, 2008 2:48 PM
Subject: What is in ubifs-2.6.git


> Hi,
>
> here is the stuff we have scheduled for 2.6.28. The
> patches
> contains various small fixes and cleanups, but there is
> something
> interesting as well.
>
> The first interesting thing is new "bulk read"
> functionality. The
> idea is that many NAND flashes support "bulk read" in some
> form.
> For example, OneNAND has "read while load" feature, which
> allows
> reading consecutive NAND pages faster than reading them
> one-by-one.
>
> So we've made UBIFS benefit from this feature and
> introduced new
> "bulk_read" mount option. With this option enabled UBIFS
> reads files
> a little ahead if the file data sits in consecutive
> physical
> addresses. For example, if user-space asks to read page
> zero of a
> file, and page 0-4 are in consecutive flash addressed,
> UBIFS reads
> pages 0-4 and populates them to the Page Cache.
>
> Note, this is disabled by default and UBIFS has to be
> explicitly
> mounted mounted with "bulk_read" option. The reason for
> this is
> that we consider this feature as experimental so far.
>
> Note, UBIFS does not use VFS read-ahead and actually
> explicitly
> disables it. This is because MTD is synchronous and all
> I/O is
> done synchronously, so read-ahead actually slows things
> down for
> UBIFS, instead of improving them. So the "bulk read"
> feature is
> basically internal UBIFS read-ahead implementation.
>
> We are able to gain 4-5MiB/s of read speed on OneNAND with
> bulk
> read enabled.
>
> The second interesting thing is new "no_chk_data_crc"
> mount option
> which disables data CRC32 checking.
>
> UBIFS always checks CRC of everything it reads from flash
> by default.
> On ARM platform this results in ~30% of total CPU usage in
> profiles,
> which is quite high. But many modern flashes are very
> reliable
> (e.g., OneNAND), and one does not need that level of
> protection.
> So now it is possible to disable CRC checking for _data_.
> However:
>
> * internal indexing information CRC is always checked;
> * when replaying the journal, data CRC is always checked;
> * on write, CRC is always calculated.
>
> With this mount option we are able to gain another
> 4-5MiB/s of read
> speed on OneNAND. And together with bulk-read, the read
> speed becomes
> ~10MiB/s faster.
>
> Adrian Hunter (11):
> UBIFS: add bulk-read facility
> UBIFS: add no_chk_data_crc mount option
> UBIFS: improve znode splitting rules
> UBIFS: correct key comparison
> UBIFS: ensure data read beyond i_size is zeroed out
> correctly
> UBIFS: allow for sync_fs when read-only
> UBIFS: improve garbage collection
> UBIFS: fix bulk-read handling uptodate pages
> UBIFS: add more debugging messages for LPT
> UBIFS: correct condition to eliminate unecessary
> assignment
> UBIFS: check buffer length when scanning for LPT
> nodes
>
> Artem Bityutskiy (9):
> UBIFS: add a print, fix comments and more minor stuff
> UBIFS: inline one-line functions
> UBIFS: check data CRC when in error state
> UBIFS: use bit-fields when possible
> UBIFS: fix races in bit-fields
> UBIFS: fix commentary
> UBIFS: update dbg_dump_inode
> UBIFS: correct comment for commit_on_unmount
> UBIFS: commit on sync_fs
>
> Hirofumi Nakagawa (1):
> UBIFS: remove unneeded unlikely()
>
> Julien Brunel (1):
> UBIFS: use an IS_ERR test rather than a NULL test
>
> Documentation/filesystems/ubifs.txt | 9 +
> fs/ubifs/budget.c | 26 ++--
> fs/ubifs/debug.c | 79 +++++++--
> fs/ubifs/debug.h | 6 +
> fs/ubifs/file.c | 260
> ++++++++++++++++++++++++++
> fs/ubifs/find.c | 4 +-
> fs/ubifs/gc.c | 90 ++++++++--
> fs/ubifs/io.c | 12 +-
> fs/ubifs/key.h | 22 ++-
> fs/ubifs/lprops.c | 34 +----
> fs/ubifs/lpt.c | 3 +-
> fs/ubifs/lpt_commit.c | 187
> ++++++++++++++++++-
> fs/ubifs/misc.h | 27 +++
> fs/ubifs/scan.c | 2 +-
> fs/ubifs/super.c | 109 +++++++++--
> fs/ubifs/tnc.c | 345
> ++++++++++++++++++++++++++++++++---
> fs/ubifs/tnc_misc.c | 4 +-
> fs/ubifs/ubifs-media.h | 1 -
> fs/ubifs/ubifs.h | 85 +++++++--
> fs/ubifs/xattr.c | 2 +-
> 20 files changed, 1149 insertions(+), 158 deletions(-)
>
> --
> Best regards,
> Artem Bityutskiy (?龜???克龜橘 ????劇)
>
>


--------------------------------------------------------------------------------


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