perf-timechart(1) ================= NAME ---- perf-timechart - Tool to visualize total system behavior during a workload SYNOPSIS -------- [verse] 'perf timechart' [] {record} [] DESCRIPTION ----------- There are two variants of perf timechart: 'perf timechart record ' to record the system level events of an arbitrary workload. By default timechart records only scheduler and CPU events (task switches, running times, CPU power states, etc), but it's possible to record IO (disk, network) activity using -I argument. 'perf timechart' to turn a trace into a Scalable Vector Graphics file, that can be viewed with popular SVG viewers such as 'Inkscape'. Depending on the events in the perf.data file, timechart will contain scheduler/cpu events or IO events. In IO mode, every bar has two charts: upper and lower. Upper bar shows incoming events (disk reads, ingress network packets). Lower bar shows outgoing events (disk writes, egress network packets). There are also poll bars which show how much time application spent in poll/epoll/select syscalls. TIMECHART OPTIONS ----------------- -o:: --output=:: Select the output file (default: output.svg) -i:: --input=:: Select the input file (default: perf.data unless stdin is a fifo) -w:: --width=:: Select the width of the SVG file (default: 1000) -P:: --power-only:: Only output the CPU power section of the diagram -T:: --tasks-only:: Don't output processor state transitions -p:: --process:: Select the processes to display, by name or PID --symfs=:: Look for files with symbols relative to this directory. -n:: --proc-num:: Print task info for at least given number of tasks. -t:: --topology:: Sort CPUs according to topology. --highlight=:: Highlight tasks (using different color) that run more than given duration or tasks with given name. If number is given it's interpreted as number of nanoseconds. If non-numeric string is given it's interpreted as task name. --io-skip-eagain:: Don't draw EAGAIN IO events. --io-min-time=:: Draw small events as if they lasted min-time. Useful when you need to see very small and fast IO. It's possible to specify ms or us suffix to specify time in milliseconds or microseconds. Default value is 1ms. --io-merge-dist=:: Merge events that are merge-dist nanoseconds apart. Reduces number of figures on the SVG and makes it more render-friendly. It's possible to specify ms or us suffix to specify time in milliseconds or microseconds. Default value is 1us. RECORD OPTIONS -------------- -P:: --power-only:: Record only power-related events -T:: --tasks-only:: Record only tasks-related events -I:: --io-only:: Record only io-related events -g:: --callchain:: Do call-graph (stack chain/backtrace) recording EXAMPLES -------- $ perf timechart record git pull [ perf record: Woken up 13 times to write data ] [ perf record: Captured and wrote 4.253 MB perf.data (~185801 samples) ] $ perf timechart Written 10.2 seconds of trace to output.svg. Record system-wide timechart: $ perf timechart record then generate timechart and highlight 'gcc' tasks: $ perf timechart --highlight gcc Record system-wide IO events: $ perf timechart record -I then generate timechart: $ perf timechart SEE ALSO -------- linkperf:perf-record[1] value='nds-private-remove'/>
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authorLinus Torvalds <torvalds@linux-foundation.org>2017-01-29 13:50:06 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-01-29 13:50:06 -0800
commit39cb2c9a316e77f6dfba96c543e55b6672d5a37e (patch)
tree98fe974ee4e20121253de7f61fc8d01bdb3821c1 /net/ipv4/tcp_bic.c
parent2c5d9555d6d937966d79d4c6529a5f7b9206e405 (diff)
drm/i915: Check for NULL i915_vma in intel_unpin_fb_obj()
I've seen this trigger twice now, where the i915_gem_object_to_ggtt() call in intel_unpin_fb_obj() returns NULL, resulting in an oops immediately afterwards as the (inlined) call to i915_vma_unpin_fence() tries to dereference it. It seems to be some race condition where the object is going away at shutdown time, since both times happened when shutting down the X server. The call chains were different: - VT ioctl(KDSETMODE, KD_TEXT): intel_cleanup_plane_fb+0x5b/0xa0 [i915] drm_atomic_helper_cleanup_planes+0x6f/0x90 [drm_kms_helper] intel_atomic_commit_tail+0x749/0xfe0 [i915] intel_atomic_commit+0x3cb/0x4f0 [i915] drm_atomic_commit+0x4b/0x50 [drm] restore_fbdev_mode+0x14c/0x2a0 [drm_kms_helper] drm_fb_helper_restore_fbdev_mode_unlocked+0x34/0x80 [drm_kms_helper] drm_fb_helper_set_par+0x2d/0x60 [drm_kms_helper] intel_fbdev_set_par+0x18/0x70 [i915] fb_set_var+0x236/0x460 fbcon_blank+0x30f/0x350 do_unblank_screen+0xd2/0x1a0 vt_ioctl+0x507/0x12a0 tty_ioctl+0x355/0xc30 do_vfs_ioctl+0xa3/0x5e0 SyS_ioctl+0x79/0x90 entry_SYSCALL_64_fastpath+0x13/0x94 - i915 unpin_work workqueue: intel_unpin_work_fn+0x58/0x140 [i915] process_one_work+0x1f1/0x480 worker_thread+0x48/0x4d0 kthread+0x101/0x140 and this patch purely papers over the issue by adding a NULL pointer check and a WARN_ON_ONCE() to avoid the oops that would then generally make the machine unresponsive. Other callers of i915_gem_object_to_ggtt() seem to also check for the returned pointer being NULL and warn about it, so this clearly has happened before in other places. [ Reported it originally to the i915 developers on Jan 8, applying the ugly workaround on my own now after triggering the problem for the second time with no feedback. This is likely to be the same bug reported as https://bugs.freedesktop.org/show_bug.cgi?id=98829 https://bugs.freedesktop.org/show_bug.cgi?id=99134 which has a patch for the underlying problem, but it hasn't gotten to me, so I'm applying the workaround. ] Cc: Daniel Vetter <daniel.vetter@intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: Imre Deak <imre.deak@intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'net/ipv4/tcp_bic.c')