commit 14315592009c17035cac81f4954d5a1f4d71e489 upstream.
Distros generally (I looked at Debian, RHEL5 and SLES11) seem to
enable CONFIG_HIGHPTE for any x86 configuration which has highmem
enabled. This means that the overhead applies even to machines which
have a fairly modest amount of high memory and which therefore do not
really benefit from allocating PTEs in high memory but still pay the
price of the additional mapping operations.
Running kernbench on a 4G box I found that with CONFIG_HIGHPTE=y but
no actual highptes being allocated there was a reduction in system
time used from 59.737s to 55.9s.
With CONFIG_HIGHPTE=y and highmem PTEs being allocated:
Average Optimal load -j 4 Run (std deviation):
Elapsed Time 175.396 (0.238914)
User Time 515.983 (5.85019)
System Time 59.737 (1.26727)
Percent CPU 263.8 (71.6796)
Context Switches 39989.7 (4672.64)
Sleeps 42617.7 (246.307)
With CONFIG_HIGHPTE=y but with no highmem PTEs being allocated:
Average Optimal load -j 4 Run (std deviation):
Elapsed Time 174.278 (0.831968)
User Time 515.659 (6.07012)
System Time 55.9 (1.07799)
Percent CPU 263.8 (71.266)
Context Switches 39929.6 (4485.13)
Sleeps 42583.7 (373.039)
This patch allows the user to control the allocation of PTEs in
highmem from the command line ("userpte=nohigh") but retains the
status-quo as the default.
It is possible that some simple heuristic could be developed which
allows auto-tuning of this option however I don't have a sufficiently
large machine available to me to perform any particularly meaningful
experiments. We could probably handwave up an argument for a threshold
at 16G of total RAM.
Assuming 768M of lowmem we have 196608 potential lowmem PTE
pages. Each page can map 2M of RAM in a PAE-enabled configuration,
meaning a maximum of 384G of RAM could potentially be mapped using
lowmem PTEs.
Even allowing generous factor of 10 to account for other required
lowmem allocations, generous slop to account for page sharing (which
reduces the total amount of RAM mappable by a given number of PT
pages) and other innacuracies in the estimations it would seem that
even a 32G machine would not have a particularly pressing need for
highmem PTEs. I think 32G could be considered to be at the upper bound
of what might be sensible on a 32 bit machine (although I think in
practice 64G is still supported).
It's seems questionable if HIGHPTE is even a win for any amount of RAM
you would sensibly run a 32 bit kernel on rather than going 64 bit.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
LKML-Reference: <1266403090-20162-1-git-send-email-ian.campbell@citrix.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Some glibc versions intentionally create lots of alignment faults in their gconv code, which if not fixed up, results in segfaults during boot. This can prevent systems booting properly. There is no clear hard-configurable default for this; the desired default depends on the nature of the userspace which is going to be booted. So, provide a way for the alignment fault handler to be configured via the kernel command line. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Allow platforms not listed in DMI table to opt-in and evaluate _PDC early. Signed-off-by: Alex Chiang <achiang@hp.com> Signed-off-by: Len Brown <len.brown@intel.com>
Introduce kernel parameter acpi_sleep=sci_force_enable some laptop requires SCI_EN being set directly on resume, or else they hung somewhere in the resume code path. We already have a blacklist for these laptops but we still need this option, especially when debugging some suspend/resume problems, in case there are systems that need this workaround and are not yet in the blacklist. Signed-off-by: Zhang Rui <rui.zhang@intel.com> Acked-by: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: Len Brown <len.brown@intel.com>
* 'for-2.6.33' of git://linux-nfs.org/~bfields/linux: (42 commits) nfsd: remove pointless paths in file headers nfsd: move most of nfsfh.h to fs/nfsd nfsd: remove unused field rq_reffh nfsd: enable V4ROOT exports nfsd: make V4ROOT exports read-only nfsd: restrict filehandles accepted in V4ROOT case nfsd: allow exports of symlinks nfsd: filter readdir results in V4ROOT case nfsd: filter lookup results in V4ROOT case nfsd4: don't continue "under" mounts in V4ROOT case nfsd: introduce export flag for v4 pseudoroot nfsd: let "insecure" flag vary by pseudoflavor nfsd: new interface to advertise export features nfsd: Move private headers to source directory vfs: nfsctl.c un-used nfsd #includes lockd: Remove un-used nfsd headers #includes s390: remove un-used nfsd #includes sparc: remove un-used nfsd #includes parsic: remove un-used nfsd #includes compat.c: Remove dependence on nfsd private headers ...
For embedded systems, the blinking cursor at startup time can be annoying and unintended. Add a new kernel parameter to change the default cursor shape. Signed-off-by: Clemens Ladisch <clemens@ladisch.de> Cc: Daniel Mack <daniel@caiaq.de> Acked-by: Pavel Machek <pavel@ucw.cz> Cc: David Newall <davidn@davidnewall.com> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Greg Kroah-Hartman <gregkh@suse.de> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'omap-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap-2.6: (75 commits) omap3: Fix OMAP35XX_REV macros omap: serial: fix non-empty uart fifo read abort omap3: Zoom2/3: Update hsmmc board config params omap3 : Enable TWL4030 Keypad for Zoom2 and Zoom3 boards omap3: id code detection 3525 vs 3515 omap3: rx51: Use wl1251 in SPI mode 3 omap3: zoom2/3: make MMC slot work again omap1: htcherald: Update defconfig to include mux support omap1: LCD_DMA: Use some define rather than a hexadecimal omap: header: remove unused data-type omap: arch/arm/plat-omap/devices.c - sort alphabetically omap: Correcting GPMC_CONFIG1_DEVICETYPE_NAND OMAP3: serial - allow platforms specify which UARTs to initialize omap3: cm-t35: add mux initialization OMAP4: Sync up omap4430 defconfig OMAP4: Remove the secondary wait loop OMAP4: AuxCoreBoot registers only accessible in secure mode OMAP4: Fix SRAM base and size OMAP4: Fix cpu detection omap3: pandora: board file updates for .33 ...
Initially only for 34xx. This code allows us to: - Make the code more generic as the omap internal signal names can stay the same across omap generations for some devices - Map mux registers to GPIO registers that is needed for dynamic muxing of pins during off-idle - Override bootloader mux values via kernel cmdline using omap_mux=some.signa1=0x1234,some.signal2=0x1234 - View and set the mux registers via debugfs if CONFIG_DEBUG_FS is enabled Cc: Mike Rapoport <mike@compulab.co.il> Cc: Benoit Cousson <b-cousson@ti.com> Signed-off-by: Paul Walmsley <paul@pwsan.com> Signed-off-by: Tony Lindgren <tony@atomide.com>
This patch (as1311) fixes a problem in usb-storage: Some devices are pretty broken when it comes to reporting sense data. The information they send back indicates that they have more than 18 bytes of sense data available, but when the system asks for more than 18 they fail or hang. The symptom is that probing fails with multiple resets. The patch adds a new BAD_SENSE flag to indicate that usb-storage should never ask for more than 18 bytes of sense data. The flag can be set in an unusual_devs entry or via the "quirks=" module parameter, and it is set automatically whenever a REQUEST SENSE command for more than 18 bytes fails or times out. An unusual_devs entry is added for the Agfa photo frame, which uses a Prolific chip having this bug. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Tested-by: Daniel Kukula <daniel.kuku@gmail.com> Cc: stable <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
* 'x86-setup-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: vgacon: Add support for setting the default cursor state vc: Add support for hiding the cursor when creating VTs x86, setup: Store the boot cursor state