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alistair23-linux/drivers
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Dave Airlie dd0c41f8a7 efifb: allow user to disable write combined mapping. 
This patch allows the user to disable write combined mapping
of the efifb framebuffer console using an nowc option.

A customer noticed major slowdowns while logging to the console
with write combining enabled, on other tasks running on the same
CPU. (10x or greater slow down on all other cores on the same CPU
as is doing the logging).

I reproduced this on a machine with dual CPUs.
Intel(R) Xeon(R) CPU E5-2609 v3 @ 1.90GHz (6 core)

I wrote a test that just mmaps the pci bar and writes to it in
a loop, while this was running in the background one a single
core with (taskset -c 1), building a kernel up to init/version.o
(taskset -c 8) went from 13s to 133s or so. I've yet to explain
why this occurs or what is going wrong I haven't managed to find
a perf command that in any way gives insight into this.

    11,885,070,715      instructions              #    1.39  insns per cycle
vs
    12,082,592,342      instructions              #    0.13  insns per cycle

is the only thing I've spotted of interest, I've tried at least:
dTLB-stores,dTLB-store-misses,L1-dcache-stores,LLC-store,LLC-store-misses,LLC-load-misses,LLC-loads,\mem-loads,mem-stores,iTLB-loads,iTLB-load-misses,cache-references,cache-misses

For now it seems at least a good idea to allow a user to disable write
combining if they see this until we can figure it out.

Note also most users get a real framebuffer driver loaded when kms
kicks in, it just happens on these machines the kernel didn't support
the gpu specific driver.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Acked-by: Peter Jones <pjones@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
 		2017-07-31 18:45:41 +02:00
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accessibility
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acpi Merge branches 'acpi-pm' and 'acpi-numa' 2017-07-27 23:14:08 +02:00
amba
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android binder: Use wake up hint for synchronous transactions. 2017-07-17 14:44:19 +02:00
ata Merge branch 'for-4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata 2017-07-06 09:41:58 -07:00
atm atm: zatm: Fix an error handling path in 'zatm_init_one()' 2017-07-18 11:37:46 -07:00
auxdisplay
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base dma mapping fixes for 4.13-rc2: 2017-07-25 17:17:18 -07:00
bcma
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block Merge branch 'for-linus' of git://git.kernel.dk/linux-block 2017-07-28 12:13:34 -07:00
bluetooth Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2017-07-05 12:31:59 -07:00
bus main drm pull for v4.13 2017-07-09 18:48:37 -07:00
cdrom block: don't set bounce limit in blk_init_queue 2017-06-27 12:13:45 -06:00
char Add wait_for_random_bytes() and get_random_*_wait() functions so that 2017-07-15 12:44:02 -07:00
clk Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2017-07-15 10:59:54 -07:00
clocksource clocksource/drivers/timer-of: Handle of_irq_get_byname() result correctly 2017-07-17 22:43:00 +02:00
connector
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cpufreq Merge branches 'intel_pstate' and 'pm-domains' 2017-07-20 18:57:15 +02:00
cpuidle powerpc updates for 4.13 2017-07-07 13:55:45 -07:00
crypto crypto: brcm - remove BCM_PDC_MBOX dependency in Kconfig 2017-07-18 17:01:08 +08:00
dax - A few DM integrity fixes that improve performance. One that address 2017-07-28 12:17:17 -07:00
dca
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devfreq PM / devfreq: constify attribute_group structures. 2017-07-06 10:17:24 +09:00
dio
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dma dmaengine updates for 4.13-rc1 2017-07-08 12:36:50 -07:00
dma-buf Merge branch 'drm-misc-next-fixes' into drm-misc-fixes 2017-07-17 11:56:07 -04:00
edac EDAC, pnd2: Fix Apollo Lake DIMM detection 2017-06-29 10:37:50 +02:00
eisa
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extcon
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firewire
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firmware efi: avoid fortify checks in EFI stub 2017-07-12 16:26:02 -07:00
fmc
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fpga
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fsi drivers/fsi: fix fsi_slave_mode prototype 2017-07-17 16:13:54 +02:00
gpio Merge (most of) tag 'mfd-next-4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd 2017-07-07 13:30:05 -07:00
gpu Summary: 2017-07-28 12:32:59 +10:00
hid HID: ortek: add one more buggy device 2017-07-24 17:38:21 +02:00
hsi HSI changes for the v4.13 series 2017-07-04 14:28:22 -07:00
hv vmbus: re-enable channel tasklet 2017-07-17 15:00:47 +02:00
hwmon hwmon: (applesmc) Avoid buffer overruns 2017-07-15 16:38:56 -07:00
hwspinlock
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hwtracing Char/Misc patches for 4.13-rc1 2017-07-03 20:55:59 -07:00
i2c Merge branch 'i2c/for-4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux 2017-07-12 10:04:56 -07:00
ide ide: avoid warning for timings calculation 2017-07-21 04:37:22 +01:00
idle intel_idle: Use more common logging style 2017-06-29 22:58:35 +02:00
iio hwmon updates for v4.13: 2017-07-04 11:48:27 -07:00
infiniband RDMA/core: Initialize port_num in qp_attr 2017-07-20 11:24:13 -04:00
input Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2017-07-14 22:53:37 -07:00
iommu IOMMU Updates for Linux v4.13 2017-07-12 10:00:04 -07:00
ipack
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irqchip irqchip/digicolor: Drop unnecessary static 2017-07-18 21:59:23 +02:00
isdn isdn: avm: c4: constify pci_device_id. 2017-07-15 21:25:56 -07:00
leds LED updates for 4.13 2017-07-06 11:32:40 -07:00
lguest
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lightnvm lightnvm: pblk: advance bio according to lba index 2017-07-28 08:06:00 -06:00
macintosh Merge branch 'work.misc-set_fs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-07-05 13:13:32 -07:00
mailbox Merge branch 'mailbox-for-next' of git://git.linaro.org/landing-teams/working/fujitsu/integration 2017-07-07 10:24:07 -07:00
mcb
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md Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md 2017-07-28 12:24:21 -07:00
media main drm pull for v4.13 2017-07-09 18:48:37 -07:00
memory ARM: SoC driver updates 2017-07-04 14:47:47 -07:00
memstick
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message
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mfd chrome-platform-for-linus-4.13 2017-07-11 09:55:47 -07:00
misc powerpc updates for 4.13 2017-07-07 13:55:45 -07:00
mmc mmc: dw_mmc: fix the wrong condition check of getting num-slots from DT 2017-07-27 15:57:30 +02:00
mtd MTD updates for v4.13-rc1: 2017-07-13 12:07:44 -07:00
mux mux: mux-core: unregister mux_class in mux_exit() 2017-07-17 16:38:35 +02:00
net virtio-net: fix module unloading 2017-07-25 16:37:36 +03:00
nfc NFC 4.13 pull request 2017-07-01 14:30:39 -07:00
ntb ntb: Add error path/handling to Debug FS entry creation 2017-07-06 11:30:08 -04:00
nubus
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nvdimm libnvdimm: fix badblock range handling of ARS range 2017-07-17 11:43:58 -07:00
nvme nvme: validate admin queue before unquiesce 2017-07-26 17:41:41 +02:00
nvmem nvmem: rockchip-efuse: amend compatible rk322x-efuse to rk3228-efuse 2017-07-17 16:15:57 +02:00
of of: irq: fix of_irq_to_resource() error check 2017-07-21 16:58:55 -05:00
oprofile
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parisc parisc: pdc_stable: constify attribute_group structures. 2017-07-23 21:02:17 +02:00
parport
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pci Power management fixes for v4.13-rc1 2017-07-14 22:24:25 -07:00
pcmcia
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perf drivers/perf: arm_pmu: Request PMU SPIs with IRQF_PER_CPU 2017-07-27 13:43:22 +01:00
phy
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pinctrl This is the big bulk of pin control changes for the v4.13 series: 2017-07-06 11:38:59 -07:00
platform Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2017-07-15 10:59:54 -07:00
pnp This is the bulk of GPIO changes for the v4.13 series: 2017-07-07 12:40:27 -07:00
power power supply and reset changes for the v4.13 series (part 2) 2017-07-13 11:47:59 -07:00
powercap powercap/RAPL: prevent overridding bits outside of the mask 2017-06-28 00:38:34 +02:00
pps
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ps3
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ptp ptp: dte: Use LL suffix for 64-bit constants 2017-07-06 11:40:58 +01:00
pwm pwm: Changes for v4.13-rc1 2017-07-13 11:49:52 -07:00
rapidio
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ras arm64 updates for 4.13: 2017-07-05 17:09:27 -07:00
regulator Merge remote-tracking branches 'regulator/topic/settle', 'regulator/topic/tps65910' and 'regulator/topic/tps65917' into regulator-next 2017-07-03 16:52:21 +01:00
remoteproc remoteproc/keystone: Fix circular dependencies for ARM configs 2017-06-27 16:21:34 -07:00
reset ARM: SoC driver updates 2017-07-04 14:47:47 -07:00
rpmsg rpmsg updates for v4.13 2017-07-06 15:38:31 -07:00
rtc RTC for 4.13 2017-07-13 12:15:06 -07:00
s390 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux 2017-07-25 08:44:27 -07:00
sbus block: don't set bounce limit in blk_init_queue 2017-06-27 12:13:45 -06:00
scsi SCSI fixes on 20170725 2017-07-25 20:10:10 -07:00
sfi
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sh drivers/sh/intc/virq.c: delete an error message for a failed memory allocation in add_virq_to_pirq() 2017-07-06 16:24:30 -07:00
sn
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soc ARM: SoC driver updates 2017-07-04 14:47:47 -07:00
spi Merge branch 'for-spi' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-07-08 10:41:53 -07:00
spmi spmi: pmic-arb: Always allocate ppid_to_apid table 2017-07-17 15:00:47 +02:00
ssb
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staging staging: rtl8188eu: add TL-WN722N v2 support 2017-07-18 09:04:22 +02:00
target Add wait_for_random_bytes() and get_random_*_wait() functions so that 2017-07-15 12:44:02 -07:00
tc
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tee
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thermal Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux 2017-07-14 13:12:32 -07:00
thunderbolt uuid fixups: 2017-07-25 19:46:05 -07:00
tty tty: hide unused pty_get_peer function 2017-07-17 17:04:41 +02:00
uio
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usb xhci: fix memleak in xhci_run() 2017-07-20 14:40:36 +02:00
uwb driver core patches for 4.13-rc1 2017-07-03 20:27:48 -07:00
vfio VFIO updates for v4.13-rc1 2017-07-13 12:23:54 -07:00
vhost Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2017-07-13 14:27:32 -07:00
video efifb: allow user to disable write combined mapping. 2017-07-31 18:45:41 +02:00
virt
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virtio virtio-balloon: coding format cleanup 2017-07-25 16:37:35 +03:00
vlynq
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vme
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w1 w1: omap-hdq: fix error return code in omap_hdq_probe() 2017-07-17 16:48:15 +02:00
watchdog Merge git://www.linux-watchdog.org/linux-watchdog 2017-07-11 09:59:37 -07:00
xen xen: dont fiddle with event channel masking in suspend/resume 2017-07-27 19:55:46 +02:00
zorro
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Kconfig
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Makefile
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