1. 22 11月, 2006 1 次提交
  2. 18 10月, 2006 1 次提交
  3. 05 10月, 2006 1 次提交
    • D
      IRQ: Maintain regs pointer globally rather than passing to IRQ handlers · 7d12e780
      David Howells 提交于
      Maintain a per-CPU global "struct pt_regs *" variable which can be used instead
      of passing regs around manually through all ~1800 interrupt handlers in the
      Linux kernel.
      
      The regs pointer is used in few places, but it potentially costs both stack
      space and code to pass it around.  On the FRV arch, removing the regs parameter
      from all the genirq function results in a 20% speed up of the IRQ exit path
      (ie: from leaving timer_interrupt() to leaving do_IRQ()).
      
      Where appropriate, an arch may override the generic storage facility and do
      something different with the variable.  On FRV, for instance, the address is
      maintained in GR28 at all times inside the kernel as part of general exception
      handling.
      
      Having looked over the code, it appears that the parameter may be handed down
      through up to twenty or so layers of functions.  Consider a USB character
      device attached to a USB hub, attached to a USB controller that posts its
      interrupts through a cascaded auxiliary interrupt controller.  A character
      device driver may want to pass regs to the sysrq handler through the input
      layer which adds another few layers of parameter passing.
      
      I've build this code with allyesconfig for x86_64 and i386.  I've runtested the
      main part of the code on FRV and i386, though I can't test most of the drivers.
      I've also done partial conversion for powerpc and MIPS - these at least compile
      with minimal configurations.
      
      This will affect all archs.  Mostly the changes should be relatively easy.
      Take do_IRQ(), store the regs pointer at the beginning, saving the old one:
      
      	struct pt_regs *old_regs = set_irq_regs(regs);
      
      And put the old one back at the end:
      
      	set_irq_regs(old_regs);
      
      Don't pass regs through to generic_handle_irq() or __do_IRQ().
      
      In timer_interrupt(), this sort of change will be necessary:
      
      	-	update_process_times(user_mode(regs));
      	-	profile_tick(CPU_PROFILING, regs);
      	+	update_process_times(user_mode(get_irq_regs()));
      	+	profile_tick(CPU_PROFILING);
      
      I'd like to move update_process_times()'s use of get_irq_regs() into itself,
      except that i386, alone of the archs, uses something other than user_mode().
      
      Some notes on the interrupt handling in the drivers:
      
       (*) input_dev() is now gone entirely.  The regs pointer is no longer stored in
           the input_dev struct.
      
       (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking.  It does
           something different depending on whether it's been supplied with a regs
           pointer or not.
      
       (*) Various IRQ handler function pointers have been moved to type
           irq_handler_t.
      Signed-Off-By: NDavid Howells <dhowells@redhat.com>
      (cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
      7d12e780
  4. 01 2月, 2006 6 次提交
  5. 05 1月, 2006 1 次提交
  6. 30 11月, 2005 1 次提交
  7. 09 9月, 2005 1 次提交
    • A
      [PATCH] USB: URB_ASYNC_UNLINK flag removed from the kernel · b375a049
      Alan Stern 提交于
      29 July 2005, Cambridge, MA:
      
      This afternoon Alan Stern submitted a patch to remove the URB_ASYNC_UNLINK
      flag from the Linux kernel.  Mr. Stern explained, "This flag is a relic
      from an earlier, less-well-designed system.  For over a year it hasn't
      been used for anything other than printing warning messages."
      
      An anonymous spokesman for the Linux kernel development community
      commented, "This is exactly the sort of thing we see happening all the
      time.  As the kernel evolves, support for old techniques and old code can
      be jettisoned and replaced by newer, better approaches.  Proprietary
      operating systems do not have the freedom or flexibility to change so
      quickly."
      
      Mr. Stern, a staff member at Harvard University's Rowland Institute who
      works on Linux only as a hobby, noted that the patch (labelled as548) did
      not update two files, keyspan.c and option.c, in the USB drivers' "serial"
      subdirectory.  "Those files need more extensive changes," he remarked.
      "They examine the status field of several URBs at times when they're not
      supposed to.  That will need to be fixed before the URB_ASYNC_UNLINK flag
      is removed."
      
      Greg Kroah-Hartman, the kernel maintainer responsible for overseeing all
      of Linux's USB drivers, did not respond to our inquiries or return our
      calls.  His only comment was "Applied, thanks."
      Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
      Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>
      b375a049
  8. 13 7月, 2005 1 次提交
  9. 28 6月, 2005 1 次提交