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  1. 17 11月, 2011 1 次提交
    • W
      writeback: hard throttle 1000+ dd on a slow USB stick · 1df64719
      由 Wu Fengguang 提交于 
      The sleep based balance_dirty_pages() can pause at most MAX_PAUSE=200ms
on every 1 4KB-page, which means it cannot throttle a task under
4KB/200ms=20KB/s. So when there are more than 512 dd writing to a
10MB/s USB stick, its bdi dirty pages could grow out of control.

Even if we can increase MAX_PAUSE, the minimal (task_ratelimit = 1)
means a limit of 4KB/s.
                                                       
They can eventually be safeguarded by the global limit check 
(nr_dirty < dirty_thresh). However if someone is also writing to an 
HDD at the same time, it'll get poor HDD write performance.
                                                       
We at least want to maintain good write performance for other devices
when one device is attacked by some "massive parallel" workload, or
suffers from slow write bandwidth, or somehow get stalled due to some 
error condition (eg. NFS server not responding).

For a stalled device, we need to completely block its dirtiers, too,
before its bdi dirty pages grow all the way up to the global limit and
leave no space for the other functional devices.

So change the loop exit condition to

	/*
	 * Always enforce global dirty limit; also enforce bdi dirty limit
	 * if the normal max_pause sleeps cannot keep things under control.
	 */
	if (nr_dirty < dirty_thresh &&
	    (bdi_dirty < bdi_thresh || bdi->dirty_ratelimit > 1))
		break;

which can be further simplified to

	if (task_ratelimit)
		break;
Signed-off-by: NWu Fengguang <fengguang.wu@intel.com>
      1df64719
  3. 16 11月, 2011 21 次提交
  5. 15 11月, 2011 1 次提交
    • L
      fsl-rio: fix compile error · e0ce42e1
      由 Liu Gang 提交于 
      The "#include <linux/module.h>" was replaced by "#include <linux/export.h>"
in the patch "powerpc: various straight conversions from module.h --> export.h".
This will cause the following compile problem:
arch/powerpc/sysdev/fsl_rio.c: In function 'fsl_rio_mcheck_exception':
arch/powerpc/sysdev/fsl_rio.c:296: error: implicit declaration of function 'search_exception_tables'.

The file fsl_rio.c needs the declaration of function "search_exception_tables"
in the header file "linux/module.h".
Signed-off-by: NLiu Gang <Gang.Liu@freescale.com>
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>
      e0ce42e1
  7. 14 11月, 2011 17 次提交