search for: rwsem_down_write_failed

...3 12:41:25 sp2 kernel: d9d18000 bf384f01 00000ceb 0000b2f9 00000001 d9d1810c c2013ac4 edc5de40 Apr 3 12:41:25 sp2 kernel: 08515c98 c6cb37b8 c2014464 c200cc80 00000020 00000000 00000000 00000000 Apr 3 12:41:25 sp2 kernel: Call Trace: Apr 3 12:41:25 sp2 kernel: [<c0622f16>] rwsem_down_write_failed+0x126/0x141 Apr 3 12:41:25 sp2 kernel: [<c0439989>] .text.lock.rwsem+0x2b/0x3a Apr 3 12:41:25 sp2 kernel: [<c046aa6a>] sys_mprotect+0xbd/0x1eb Apr 3 12:41:25 sp2 kernel: [<c0404f4b>] syscall_call+0x7/0xb Apr 3 12:41:25 sp2 kernel: ======================= Apr 3 12:41:2...

...Long wrote: >> It was found when running fio sequential write test with a XFS ramdisk >> on a VM running on a 2-socket x86-64 system, the %CPU times as reported >> by perf were as follows: >> >> 69.75% 0.59% fio [k] down_write >> 69.15% 0.01% fio [k] call_rwsem_down_write_failed >> 67.12% 1.12% fio [k] rwsem_down_write_failed >> 63.48% 52.77% fio [k] osq_lock >> 9.46% 7.88% fio [k] __raw_callee_save___kvm_vcpu_is_preempt >> 3.93% 3.93% fio [k] __kvm_vcpu_is_preempted >> > Thinking about this again, wouldn't something li...

...Long wrote: >> It was found when running fio sequential write test with a XFS ramdisk >> on a VM running on a 2-socket x86-64 system, the %CPU times as reported >> by perf were as follows: >> >> 69.75% 0.59% fio [k] down_write >> 69.15% 0.01% fio [k] call_rwsem_down_write_failed >> 67.12% 1.12% fio [k] rwsem_down_write_failed >> 63.48% 52.77% fio [k] osq_lock >> 9.46% 7.88% fio [k] __raw_callee_save___kvm_vcpu_is_preempt >> 3.93% 3.93% fio [k] __kvm_vcpu_is_preempted >> > Thinking about this again, wouldn't something li...

It was found when running fio sequential write test with a XFS ramdisk on a VM running on a 2-socket x86-64 system, the %CPU times as reported by perf were as follows: 69.75% 0.59% fio [k] down_write 69.15% 0.01% fio [k] call_rwsem_down_write_failed 67.12% 1.12% fio [k] rwsem_down_write_failed 63.48% 52.77% fio [k] osq_lock 9.46% 7.88% fio [k] __raw_callee_save___kvm_vcpu_is_preempt 3.93% 3.93% fio [k] __kvm_vcpu_is_preempted Making vcpu_is_preempted() a callee-save function has a relatively high cost on x86-64 primarily due...

It was found when running fio sequential write test with a XFS ramdisk on a VM running on a 2-socket x86-64 system, the %CPU times as reported by perf were as follows: 69.75% 0.59% fio [k] down_write 69.15% 0.01% fio [k] call_rwsem_down_write_failed 67.12% 1.12% fio [k] rwsem_down_write_failed 63.48% 52.77% fio [k] osq_lock 9.46% 7.88% fio [k] __raw_callee_save___kvm_vcpu_is_preempt 3.93% 3.93% fio [k] __kvm_vcpu_is_preempted Making vcpu_is_preempted() a callee-save function has a relatively high cost on x86-64 primarily due...

...It was found when running fio sequential write test with a XFS ramdisk >>> on a VM running on a 2-socket x86-64 system, the %CPU times as reported >>> by perf were as follows: >>> >>> 69.75% 0.59% fio [k] down_write >>> 69.15% 0.01% fio [k] call_rwsem_down_write_failed >>> 67.12% 1.12% fio [k] rwsem_down_write_failed >>> 63.48% 52.77% fio [k] osq_lock >>> 9.46% 7.88% fio [k] __raw_callee_save___kvm_vcpu_is_preempt >>> 3.93% 3.93% fio [k] __kvm_vcpu_is_preempted >>> >> Thinking about this again, w...

It was found when running fio sequential write test with a XFS ramdisk on a 2-socket x86-64 system, the %CPU times as reported by perf were as follows: 71.27% 0.28% fio [k] down_write 70.99% 0.01% fio [k] call_rwsem_down_write_failed 69.43% 1.18% fio [k] rwsem_down_write_failed 65.51% 54.57% fio [k] osq_lock 9.72% 7.99% fio [k] __raw_callee_save___kvm_vcpu_is_preempted 4.16% 4.16% fio [k] __kvm_vcpu_is_preempted So making vcpu_is_preempted() a callee-save function has a pretty high cost associated with it. As...

It was found when running fio sequential write test with a XFS ramdisk on a 2-socket x86-64 system, the %CPU times as reported by perf were as follows: 71.27% 0.28% fio [k] down_write 70.99% 0.01% fio [k] call_rwsem_down_write_failed 69.43% 1.18% fio [k] rwsem_down_write_failed 65.51% 54.57% fio [k] osq_lock 9.72% 7.99% fio [k] __raw_callee_save___kvm_vcpu_is_preempted 4.16% 4.16% fio [k] __kvm_vcpu_is_preempted So making vcpu_is_preempted() a callee-save function has a pretty high cost associated with it. As...

It was found when running fio sequential write test with a XFS ramdisk on a KVM guest running on a 2-socket x86-64 system, the %CPU times as reported by perf were as follows: 69.75% 0.59% fio [k] down_write 69.15% 0.01% fio [k] call_rwsem_down_write_failed 67.12% 1.12% fio [k] rwsem_down_write_failed 63.48% 52.77% fio [k] osq_lock 9.46% 7.88% fio [k] __raw_callee_save___kvm_vcpu_is_preempt 3.93% 3.93% fio [k] __kvm_vcpu_is_preempted Making vcpu_is_preempted() a callee-save function has a relatively high cost on x86-64 primarily due...

It was found when running fio sequential write test with a XFS ramdisk on a KVM guest running on a 2-socket x86-64 system, the %CPU times as reported by perf were as follows: 69.75% 0.59% fio [k] down_write 69.15% 0.01% fio [k] call_rwsem_down_write_failed 67.12% 1.12% fio [k] rwsem_down_write_failed 63.48% 52.77% fio [k] osq_lock 9.46% 7.88% fio [k] __raw_callee_save___kvm_vcpu_is_preempt 3.93% 3.93% fio [k] __kvm_vcpu_is_preempted Making vcpu_is_preempted() a callee-save function has a relatively high cost on x86-64 primarily due...

.... That function is simple enough that > making __kvm_vcpu_is_preempted() callee-save won't produce much compiler > optimization opportunity. This is because of that noinline, right? Otherwise it would've been folded and register pressure would be much higher. > The outer function rwsem_down_write_failed() > does appear to be a bit bigger (from 866 bytes to 884 bytes) though. I suspect GCC is being clever and since all this is static it plays games with the calling convention and pushes these clobbers out.

.... That function is simple enough that > making __kvm_vcpu_is_preempted() callee-save won't produce much compiler > optimization opportunity. This is because of that noinline, right? Otherwise it would've been folded and register pressure would be much higher. > The outer function rwsem_down_write_failed() > does appear to be a bit bigger (from 866 bytes to 884 bytes) though. I suspect GCC is being clever and since all this is static it plays games with the calling convention and pushes these clobbers out.

v3->v4: - Fix x86-32 build error. v2->v3: - Provide an optimized __raw_callee_save___kvm_vcpu_is_preempted() in assembly as suggested by PeterZ. - Add a new patch to change vcpu_is_preempted() argument type to long to ease the writing of the assembly code. v1->v2: - Rerun the fio test on a different system on both bare-metal and a KVM guest. Both sockets were

v3->v4: - Fix x86-32 build error. v2->v3: - Provide an optimized __raw_callee_save___kvm_vcpu_is_preempted() in assembly as suggested by PeterZ. - Add a new patch to change vcpu_is_preempted() argument type to long to ease the writing of the assembly code. v1->v2: - Rerun the fio test on a different system on both bare-metal and a KVM guest. Both sockets were

v2->v3: - Provide an optimized __raw_callee_save___kvm_vcpu_is_preempted() in assembly as suggested by PeterZ. - Add a new patch to change vcpu_is_preempted() argument type to long to ease the writing of the assembly code. v1->v2: - Rerun the fio test on a different system on both bare-metal and a KVM guest. Both sockets were utilized in this test. - The commit log was

v2->v3: - Provide an optimized __raw_callee_save___kvm_vcpu_is_preempted() in assembly as suggested by PeterZ. - Add a new patch to change vcpu_is_preempted() argument type to long to ease the writing of the assembly code. v1->v2: - Rerun the fio test on a different system on both bare-metal and a KVM guest. Both sockets were utilized in this test. - The commit log was

...b 08, 2017 at 01:00:24PM -0500, Waiman Long wrote: > It was found when running fio sequential write test with a XFS ramdisk > on a 2-socket x86-64 system, the %CPU times as reported by perf were > as follows: > > 71.27% 0.28% fio [k] down_write > 70.99% 0.01% fio [k] call_rwsem_down_write_failed > 69.43% 1.18% fio [k] rwsem_down_write_failed > 65.51% 54.57% fio [k] osq_lock > 9.72% 7.99% fio [k] __raw_callee_save___kvm_vcpu_is_preempted > 4.16% 4.16% fio [k] __kvm_vcpu_is_preempted > > So making vcpu_is_preempted() a callee-save function has a pretty hig...

...:43:09AM -0500, Waiman Long wrote: > It was found when running fio sequential write test with a XFS ramdisk > on a VM running on a 2-socket x86-64 system, the %CPU times as reported > by perf were as follows: > > 69.75% 0.59% fio [k] down_write > 69.15% 0.01% fio [k] call_rwsem_down_write_failed > 67.12% 1.12% fio [k] rwsem_down_write_failed > 63.48% 52.77% fio [k] osq_lock > 9.46% 7.88% fio [k] __raw_callee_save___kvm_vcpu_is_preempt > 3.93% 3.93% fio [k] __kvm_vcpu_is_preempted > Thinking about this again, wouldn't something like the below also work?...

...fff8800767396c0 ffff88007722ca50 [ 413.409157] Call Trace: [ 413.409157] [<ffffffff810c072e>] ? unlock_page+0x24/0x28 [ 413.409157] [<ffffffff810dbd38>] ? __do_fault+0x398/0x3cd [ 413.409157] [<ffffffff8161e3e4>] schedule+0x64/0x66 [ 413.409157] [<ffffffff8161ee9c>] rwsem_down_write_failed+0xf7/0x14a [ 413.409157] [<ffffffff8120d7f3>] call_rwsem_down_write_failed+0x13/0x20 [ 413.409157] [<ffffffff8161d555>] ? down_write+0x2e/0x32 [ 413.409157] [<ffffffff81105701>] thaw_super+0x1f/0xa7 [ 413.409157] [<ffffffff8111217b>] do_vfs_ioctl+0x202/0x486 [ 413.4...

...| |--1.80%-- ext4_do_update_inode | |--1.52%-- cache_flusharray | |--0.89%-- __mutex_unlock_slowpath | |--0.64%-- ttwu_queue |--11.19%-- _raw_spin_lock_irq | |--98.95%-- rwsem_down_write_failed | |--0.93%-- __schedule |--7.91%-- queue_read_lock_slowpath | _raw_read_lock | |--96.79%-- do_wait | |--2.44%-- do_prlimit | chrdev_open...