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b58a36008b
linux/drivers/char
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Stefan Wahren b58a36008b hwrng: bcm2835 - Fix hwrng throughput regression 
The last RCU stall fix caused a massive throughput regression of the
hwrng on Raspberry Pi 0 - 3. hwrng_msleep doesn't sleep precisely enough
and usleep_range doesn't allow scheduling. So try to restore the
best possible throughput by introducing hwrng_yield which interruptable
sleeps for one jiffy.

Some performance measurements on Raspberry Pi 3B+ (arm64/defconfig):

sudo dd if=/dev/hwrng of=/dev/null count=1 bs=10000

cpu_relax              ~138025 Bytes / sec
hwrng_msleep(1000)         ~13 Bytes / sec
hwrng_yield              ~2510 Bytes / sec

Fixes: 96cb9d0554 ("hwrng: bcm2835 - use hwrng_msleep() instead of cpu_relax()")
Link: https://lore.kernel.org/linux-arm-kernel/bc97ece5-44a3-4c4e-77da-2db3eb66b128@gmx.net/
Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2023-09-15 18:29:45 +08:00
..
agp char: Explicitly include correct DT includes 2023-07-30 18:15:27 +02:00
hw_random hwrng: bcm2835 - Fix hwrng throughput regression 2023-09-15 18:29:45 +08:00
ipmi Minor fixes for IPMI 2023-08-30 19:20:35 -07:00
mwave char/mwave: Adjust io port register size 2021-12-03 14:27:06 +01:00
tpm tpm: Enable hwrng only for Pluton on AMD CPUs 2023-09-04 21:57:59 +03:00
xilinx_hwicap xilinx_hwicap: make icap_class a static const structure 2023-06-23 10:27:23 +02:00
xillybus char: xillybus: make XILLYBUS_OF depend on HAS_IOMEM 2023-08-04 15:39:39 +02:00
adi.c
apm-emulation.c apm-emulation: drop unexpected word "the" in the comments 2022-06-27 16:15:27 +02:00
applicom.c applicom: Fix PCI device refcount leak in applicom_init() 2023-01-20 13:05:39 +01:00
applicom.h
bsr.c char: Explicitly include correct DT includes 2023-07-30 18:15:27 +02:00
ds1620.c
dsp56k.c dsp56k: make dsp56k_class a static const structure 2023-06-23 10:27:08 +02:00
dtlk.c
hangcheck-timer.c
hpet.c hpet: remove unused writeq/readq function definitions 2022-02-04 16:45:39 +01:00
Kconfig char: add HAS_IOPORT dependencies 2023-05-31 19:17:29 +01:00
lp.c char: lp: make lp_class a static const structure 2023-06-23 10:27:11 +02:00
Makefile char: pcmcia: remove all the drivers 2023-03-09 17:30:27 +01:00
mem.c drivers/char/mem.c: shrink character device's devlist[] array 2023-08-24 16:25:15 -07:00
misc.c char: misc: make misc_class a static const structure 2023-06-23 10:27:15 +02:00
mspec.c mm: replace vma->vm_flags direct modifications with modifier calls 2023-02-09 16:51:39 -08:00
nsc_gpio.c
nvram.c
nwbutton.c
nwbutton.h
nwflash.c
pc8736x_gpio.c
powernv-op-panel.c powerpc/powernv: Fix fall-through warning for Clang 2021-07-13 19:21:41 -05:00
ppdev.c ppdev: make ppdev_class a static const structure 2023-06-23 10:27:17 +02:00
ps3flash.c powerpc/ps3: make system bus's remove and shutdown callbacks return void 2020-12-04 01:01:22 +11:00
random.c tty, proc, kernfs, random: Use copy_splice_read() 2023-05-24 08:42:16 -06:00
scx200_gpio.c
sonypi.c ACPI: make remove callback of ACPI driver void 2022-11-23 19:11:22 +01:00
tlclk.c
toshiba.c module: remove never implemented MODULE_SUPPORTED_DEVICE 2021-03-17 13:16:18 -07:00
ttyprintk.c tty: make tty_operations::write()'s count size_t 2023-08-11 21:12:46 +02:00
uv_mmtimer.c
virtio_console.c virtio: features, fixes, cleanups 2023-07-03 15:38:26 -07:00