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] >mode:

author	James Bottomley <James.Bottomley@HansenPartnership.com>	2016-05-13 12:04:06 -0700
committer	Martin K. Petersen <martin.petersen@oracle.com>	2016-05-22 14:52:45 -0400
commit	a621bac3044ed6f7ec5fa0326491b2d4838bfa93 (patch)
tree	e8c0c7dc229c83c07bf6edb61733ff1f68ffb240
parent	97f00905ec98472050d65c46629237b299f29035 (diff)

scsi_lib: correctly retry failed zero length REQ_TYPE_FS commands

When SCSI was written, all commands coming from the filesystem (REQ_TYPE_FS commands) had data. This meant that our signal for needing to complete the command was the number of bytes completed being equal to the number of bytes in the request. Unfortunately, with the advent of flush barriers, we can now get zero length REQ_TYPE_FS commands, which confuse this logic because they satisfy the condition every time. This means they never get retried even for retryable conditions, like UNIT ATTENTION because we complete them early assuming they're done. Fix this by special casing the early completion condition to recognise zero length commands with errors and let them drop through to the retry code. Cc: stable@vger.kernel.org Reported-by: Sebastian Parschauer <s.parschauer@gmx.de> Signed-off-by: James E.J. Bottomley <jejb@linux.vnet.ibm.com> Tested-by: Jack Wang <jinpu.wang@profitbricks.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

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