Thomas Gleixner 9cc9f17a5a x86/mm/cpa: Do the range check early
To avoid excessive 4k wise checks in the common case do a quick check first
whether the requested new page protections conflict with a static
protection area in the large page. If there is no conflict then the
decision whether to preserve or to split the page can be made immediately.

If the requested range covers the full large page, preserve it. Otherwise
split it up. No point in doing a slow crawl in 4k steps.

Before:

 1G pages checked:                    2
 1G pages sameprot:                   0
 1G pages preserved:                  0
 2M pages checked:                  538
 2M pages sameprot:                 466
 2M pages preserved:                 47
 4K pages checked:               560642
 4K pages set-checked:             7668

After:

 1G pages checked:                    2
 1G pages sameprot:                   0
 1G pages preserved:                  0
 2M pages checked:                  541
 2M pages sameprot:                 466
 2M pages preserved:                 47
 4K pages checked:                  514
 4K pages set-checked:             7668

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Bin Yang <bin.yang@intel.com>
Cc: Mark Gross <mark.gross@intel.com>
Link: https://lkml.kernel.org/r/20180917143546.507259989@linutronix.de
2018-09-27 20:39:39 +02:00
2018-09-27 20:39:39 +02:00
2018-09-23 19:15:18 +02:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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