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  1. 03 Dec, 2010 2 commits
    • John Stultz's avatar
      x86: Improve TSC calibration using a delayed workqueue · 08ec0c58
      John Stultz authored 
      Boot to boot the TSC calibration may vary by quite a large amount.

While normal variance of 50-100ppm can easily be seen, the quick
calibration code only requires 500ppm accuracy, which is the limit
of what NTP can correct for.

This can cause problems for systems being used as NTP servers, as
every time they reboot it can take hours for them to calculate the
new drift error caused by the calibration.

The classic trade-off here is calibration accuracy vs slow boot times,
as during the calibration nothing else can run.

This patch uses a delayed workqueue  to calibrate the TSC over the
period of a second. This allows very accurate calibration (in my
tests only varying by 1khz or 0.4ppm boot to boot). Additionally this
refined calibration step does not block the boot process, and only
delays the TSC clocksoure registration by a few seconds in early boot.
If the refined calibration strays 1% from the early boot calibration
value, the system will fall back to already calculated early boot
calibration.

Credit to Andi Kleen who suggested using a timer quite awhile back,
but I dismissed it thinking the timer calibration would be done after
the clocksource was registered (which would break things). Forgive
me for my short-sightedness.

This patch has worked very well in my testing, but TSC hardware is
quite varied so it would probably be good to get some extended
testing, possibly pushing inclusion out to 2.6.39.
Signed-off-by: default avatarJohn Stultz <johnstul@us.ibm.com>
LKML-Reference: <1289003985-29060-1-git-send-email-johnstul@us.ibm.com>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Ingo Molnar <mingo@elte.hu>
CC: Martin Schwidefsky <schwidefsky@de.ibm.com>
CC: Clark Williams <williams@redhat.com>
CC: Andi Kleen <andi@firstfloor.org>
      08ec0c58
    • John Stultz's avatar
      Merge remote branch 'tip/x86/tsc' into fortglx/2.6.38/tip/x86/tsc · b0f96900
      John Stultz authored 
      Conflicts:
	Documentation/kernel-parameters.txt
      b0f96900
  3. 21 Nov, 2010 1 commit
  5. 20 Nov, 2010 3 commits
    • Linus Torvalds's avatar
      Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4 · b86db474
      Linus Torvalds authored 
      * 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: Add EXT4_IOC_TRIM ioctl to handle batched discard
  fs: Do not dispatch FITRIM through separate super_operation
  ext4: ext4_fill_super shouldn't return 0 on corruption
  jbd2: fix /proc/fs/jbd2/<dev> when using an external journal
  ext4: missing unlock in ext4_clear_request_list()
  ext4: fix setting random pages PageUptodate
      b86db474
    • Lukas Czerner's avatar
      ext4: Add EXT4_IOC_TRIM ioctl to handle batched discard · e681c047
      Lukas Czerner authored 
      Filesystem independent ioctl was rejected as not common enough to be in
core vfs ioctl. Since we still need to access to this functionality this
commit adds ext4 specific ioctl EXT4_IOC_TRIM to dispatch
ext4_trim_fs().

It takes fstrim_range structure as an argument. fstrim_range is definec in
the include/linux/fs.h and its definition is as follows.

struct fstrim_range {
	__u64 start;
	__u64 len;
	__u64 minlen;
}

start	- first Byte to trim
len	- number of Bytes to trim from start
minlen	- minimum extent length to trim, free extents shorter than this
  number of Bytes will be ignored. This will be rounded up to fs
  block size.

After the FITRIM is done, the number of actually discarded Bytes is stored
in fstrim_range.len to give the user better insight on how much storage
space has been really released for wear-leveling.
Signed-off-by: default avatarLukas Czerner <lczerner@redhat.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
      e681c047
    • Lukas Czerner's avatar
      fs: Do not dispatch FITRIM through separate super_operation · 93bb41f4
      Lukas Czerner authored 
      There was concern that FITRIM ioctl is not common enough to be included
in core vfs ioctl, as Christoph Hellwig pointed out there's no real point
in dispatching this out to a separate vector instead of just through
->ioctl.

So this commit removes ioctl_fstrim() from vfs ioctl and trim_fs
from super_operation structure.
Signed-off-by: default avatarLukas Czerner <lczerner@redhat.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
      93bb41f4
  7. 19 Nov, 2010 15 commits
  9. 18 Nov, 2010 19 commits
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