#
325757 |
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13-Nov-2017 |
kib |
MFC r325671: Check that the pmc index is less than the number of hardware PMCs, instead of asserting the condition.
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#
310063 |
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14-Dec-2016 |
avg |
MFC r308480: pmc_process_csw_out: ignore deleted counters
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#
300060 |
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17-May-2016 |
pfg |
MFC r298931, r298981, r299375:
Minor spelling fixes in: sys/dev, sys/sys
Many of these have user-visible strings.
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#
296730 |
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12-Mar-2016 |
kib |
MFC r295352: Do not call vn_fullpath(9) (through the pmc_getfilename() wrapper) when its result is immediately ignored, i.e. for kernel processes forked from the user process. Do not test for non-null before freeing string.
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#
294046 |
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14-Jan-2016 |
jtl |
MFC r290811: Fix hwpmc "stalled" behavior
Currently, there is a single pm_stalled flag that tracks whether a performance monitor was "stalled" due to insufficent ring buffer space for samples. However, because the same performance monitor can run on multiple processes or threads at the same time, a single pm_stalled flag that impacts them all seems insufficient.
In particular, you can hit corner cases where the code fails to stop performance monitors during a context switch out, because it thinks the performance monitor is already stopped. However, in reality, it may be that only the monitor running on a different CPU was stalled.
This patch attempts to fix that behavior by tracking on a per-CPU basis whether a PM desires to run and whether it is "stalled". This lets the code make better decisions about when to stop PMs and when to try to restart them. Ideally, we should avoid the case where the code fails to stop a PM during a context switch out.
MFC r290813: Optimizations to the way hwpmc gathers user callchains
Changes to the code to gather user stacks: * Delay setting pmc_cpumask until we actually have the stack. * When recording user stack traces, only walk the portion of the ring that should have samples for us.
MFC r290929: Change the driver stats to what they really are: unsigned values.
When pmcstat exits after some samples were dropped, give the user an idea of how many were lost. (Granted, these are global numbers, but they may still help quantify the scope of the loss.)
MFC r290930: Improve accuracy of PMC sampling frequency
The code tracks a counter which is the number of events until the next sample. On context switch in, it loads the saved counter. On context switch out, it tries to calculate a new saved counter.
Problems:
1. The saved counter was shared by all threads in a process. However, this means that all threads would be initially loaded with the same saved counter. However, that could result in sampling more often than once every X number of events.
2. The calculation to determine a new saved counter was backwards. It added when it should have subtracted, and subtracted when it should have added. Assume a single-threaded process with a reload count of 1000 events. Assuming the counter on context switch in was 100 and the counter on context switch out was 50 (meaning the thread has "consumed" 50 more events), the code would calculate a new saved counter of 150 (instead of the proper 50).
Fix:
1. As soon as the saved counter is used to initialize a monitor for a thread on context switch in, set the saved counter to the reload count. That way, subsequent threads to use the saved counter will get the full reload count, assuring we sample at least once every X number of events (across all threads).
2. Change the calculation of the saved counter. Due to the change to the saved counter in #1, we simply need to add (modulo the reload count) the remaining counter time we retrieve from the CPU when a thread is context switched out.
MFC r291016: Support a wider history counter in pmcstat(8) gmon output
pmcstat(8) contains an option to output sampling data in a gmon format compatible with gprof(1). Currently, it uses the default histcounter, which is an (unsigned short). With large sets of sampling data, it is possible to overflow the maximum value provided by an (unsigned short).
This change adds the -e argument to pmcstat. If -e and -g are both specified, pmcstat will use a histcounter type of uint64_t.
MFC r291017: Fix the date on the pmcstat(8) man page from r291016.
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#
288499 |
|
02-Oct-2015 |
vangyzen |
MFC r283924
Provide vnode in memory map info for files on tmpfs
When providing memory map information to userland, populate the vnode pointer for tmpfs files. Set the memory mapping to appear as a vnode type, to match FreeBSD 9 behavior.
This fixes the use of tmpfs files with the dtrace pid provider, procstat -v, procfs, linprocfs, pmc (pmcstat), and ptrace (PT_VM_ENTRY).
Submitted by: Eric Badger <eric@badgerio.us> (initial revision) Obtained from: Dell Inc. PR: 198431
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#
283886 |
|
01-Jun-2015 |
jhb |
MFC 283123: Fix two bugs that could result in PMC sampling effectively stopping. In both cases, the the effect of the bug was that a very small positive number was written to the counter. This means that a large number of events needed to occur before the next sampling interrupt would trigger. Even with very frequently occurring events like clock cycles wrapping all the way around could take a long time. Both bugs occurred when updating the saved reload count for an outgoing thread on a context switch.
First, the counter-independent code compares the current reload count against the count set when the thread switched in and generates a delta to apply to the saved count. If this delta causes the reload counter to go negative, it would add a full reload interval to wrap it around to a positive value. The fix is to add the full reload interval if the resulting counter is zero.
Second, occasionally the raw counter value read during a context switch has actually wrapped, but an interrupt has not yet triggered. In this case the existing logic would return a very large reload count (e.g. 2^48 - 2 if the counter had overflowed by a count of 2). This was seen both for fixed-function and programmable counters on an E5-2643. Workaround this case by returning a reload count of zero.
PR: 198149 Sponsored by: Norse Corp, Inc.
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#
283884 |
|
01-Jun-2015 |
jhb |
MFC 282641,282658: - Move hwpmc(4) debugging code under a new HWPMC_DEBUG option instead of the broader DEBUG option. - Convert hwpmc(4) debug printfs over to KTR.
Sponsored by: Norse Corp, Inc.
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#
280455 |
|
24-Mar-2015 |
rrs |
MFC of r277177 and r279894 with the fixes for the PMC for Haswell.
Sponsored by: Netflix Inc.
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#
278813 |
|
15-Feb-2015 |
emaste |
Clamp too large hwpmc callchaindepth to maximum
If the depth requested by the user is too large, it's better to provide the maximum than the smaller default.
MFC of: r274766 Sponsored by: The FreeBSD Foundation
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#
274155 |
|
05-Nov-2014 |
markj |
MFC r273236: Use pmc_destroy_pmc_descriptor() to actually free the pmc, which is consistent with pmc_destroy_owner_descriptor(). Also be sure to destroy PMCs if a process exits or execs without explicitly releasing them.
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#
288499 |
|
02-Oct-2015 |
vangyzen |
MFC r283924
Provide vnode in memory map info for files on tmpfs
When providing memory map information to userland, populate the vnode pointer for tmpfs files. Set the memory mapping to appear as a vnode type, to match FreeBSD 9 behavior.
This fixes the use of tmpfs files with the dtrace pid provider, procstat -v, procfs, linprocfs, pmc (pmcstat), and ptrace (PT_VM_ENTRY).
Submitted by: Eric Badger <eric@badgerio.us> (initial revision) Obtained from: Dell Inc. PR: 198431
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#
283886 |
|
01-Jun-2015 |
jhb |
MFC 283123: Fix two bugs that could result in PMC sampling effectively stopping. In both cases, the the effect of the bug was that a very small positive number was written to the counter. This means that a large number of events needed to occur before the next sampling interrupt would trigger. Even with very frequently occurring events like clock cycles wrapping all the way around could take a long time. Both bugs occurred when updating the saved reload count for an outgoing thread on a context switch.
First, the counter-independent code compares the current reload count against the count set when the thread switched in and generates a delta to apply to the saved count. If this delta causes the reload counter to go negative, it would add a full reload interval to wrap it around to a positive value. The fix is to add the full reload interval if the resulting counter is zero.
Second, occasionally the raw counter value read during a context switch has actually wrapped, but an interrupt has not yet triggered. In this case the existing logic would return a very large reload count (e.g. 2^48 - 2 if the counter had overflowed by a count of 2). This was seen both for fixed-function and programmable counters on an E5-2643. Workaround this case by returning a reload count of zero.
PR: 198149 Sponsored by: Norse Corp, Inc.
|
#
283884 |
|
01-Jun-2015 |
jhb |
MFC 282641,282658: - Move hwpmc(4) debugging code under a new HWPMC_DEBUG option instead of the broader DEBUG option. - Convert hwpmc(4) debug printfs over to KTR.
Sponsored by: Norse Corp, Inc.
|
#
280455 |
|
24-Mar-2015 |
rrs |
MFC of r277177 and r279894 with the fixes for the PMC for Haswell.
Sponsored by: Netflix Inc.
|
#
278813 |
|
15-Feb-2015 |
emaste |
Clamp too large hwpmc callchaindepth to maximum
If the depth requested by the user is too large, it's better to provide the maximum than the smaller default.
MFC of: r274766 Sponsored by: The FreeBSD Foundation
|
#
274155 |
|
05-Nov-2014 |
markj |
MFC r273236: Use pmc_destroy_pmc_descriptor() to actually free the pmc, which is consistent with pmc_destroy_owner_descriptor(). Also be sure to destroy PMCs if a process exits or execs without explicitly releasing them.
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