Buildresult: powerpc-next/powerpc-allnoconfig/powerpc-gcc5 built on Aug 3 2018, 20:16

kisskb

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Status:	OK
Date/Time:	Aug 3 2018, 20:16
Duration:	0:00:20.613992
Builder:	ka4
Revision:	powerpc/powernv: Fix concurrency issue with npu->mmio_atsd_usage (`a6fcdbf95d7907bc5d5a669adb86e6bda72d738b)`
Target:	powerpc-next/powerpc-allnoconfig/powerpc-gcc5
Branch:	powerpc-next
Compiler:	powerpc-gcc5 (powerpc64-linux-gcc (GCC) 5.3.0)
Config:	allnoconfig (download)
Log:	Download original No warnings found in log. Full Log # git rev-parse -q --verify a6fcdbf95d7907bc5d5a669adb86e6bda72d738b^{commit} a6fcdbf95d7907bc5d5a669adb86e6bda72d738b already have revision, skipping fetch # git checkout -q -f -B kisskb a6fcdbf95d7907bc5d5a669adb86e6bda72d738b # git clean -qxdf # < git log -1 # commit a6fcdbf95d7907bc5d5a669adb86e6bda72d738b # Author: Reza Arbab <arbab@linux.ibm.com> # Date: Thu Aug 2 23:03:36 2018 -0500 # # powerpc/powernv: Fix concurrency issue with npu->mmio_atsd_usage # # We've encountered a performance issue when multiple processors stress # {get,put}_mmio_atsd_reg(). These functions contend for # mmio_atsd_usage, an unsigned long used as a bitmask. # # The accesses to mmio_atsd_usage are done using test_and_set_bit_lock() # and clear_bit_unlock(). As implemented, both of these will require # a (successful) stwcx to that same cache line. # # What we end up with is thread A, attempting to unlock, being slowed by # other threads repeatedly attempting to lock. A's stwcx instructions # fail and retry because the memory reservation is lost every time a # different thread beats it to the punch. # # There may be a long-term way to fix this at a larger scale, but for # now resolve the immediate problem by gating our call to # test_and_set_bit_lock() with one to test_bit(), which is obviously # implemented without using a store. # # Fixes: 1ab66d1fbada ("powerpc/powernv: Introduce address translation services for Nvlink2") # Signed-off-by: Reza Arbab <arbab@linux.ibm.com> # Acked-by: Alistair Popple <alistair@popple.id.au> # Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> # < /opt/cross/kisskb/gcc-5.3.0-nolibc/powerpc64-linux/bin/powerpc64-linux-gcc --version # < git log --format=%s --max-count=1 a6fcdbf95d7907bc5d5a669adb86e6bda72d738b # < make -s -j 40 ARCH=powerpc O=/kisskb/build/powerpc-next_powerpc-allnoconfig_powerpc-5.3 CROSS_COMPILE=/opt/cross/kisskb/gcc-5.3.0-nolibc/powerpc64-linux/bin/powerpc64-linux- allnoconfig # make -s -j 40 ARCH=powerpc O=/kisskb/build/powerpc-next_powerpc-allnoconfig_powerpc-5.3 CROSS_COMPILE=/opt/cross/kisskb/gcc-5.3.0-nolibc/powerpc64-linux/bin/powerpc64-linux- /kisskb/src/net/Makefile:24: CC cannot link executables. Skipping bpfilter. Completed OK # rm -rf /kisskb/build/powerpc-next_powerpc-allnoconfig_powerpc-5.3 # Build took: 0:00:20.613992

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