Add information regarding memory disclaiming in javacore

[dev-koan]

Added a struct to J9JITConfig to store information regarding memory disclaiming. The information was collected in J9Options class and printed in java core file.

Signed-off-by: Dev Agarwal dev.agarwal@ibm.com

[dev-koan]

0SECTION       Memory disclaim info dump routine
NULL           ------------------------------------------------------------------------
1CIDISCLSUBS   Disclaim subsystem status
NULL           ------------------------------------------------------------------------
2CIDISCLDATA   Data cache disclaim:               enabled
2CIDISCLIPRO   IProfiler data disclaim:           enabled
2CIDISCLRTAM   Runtime assumption disclaim:       enabled
2CIDISCLCODE   Code cache disclaim:               disabled
2CIDISCLSCC    Shared class cache disclaim:       enabled
NULL           ------------------------------------------------------------------------
2CIDISCLBMED   Disclaim Backing medium: swap
NULL           ------------------------------------------------------------------------
1CIDISCLDEV    Backing device I/O statistics
NULL           ------------------------------------------------------------------------
2CIDISCLDEVN   Device name:                      dm-0
2CIDISCLRDIO   Read I/Os:                        6221
2CIDISCLRDTK   Read ticks (ms):                  4193
2CIDISCLWRIO   Write I/Os:                       50599
2CIDISCLWRTK   Write ticks (ms):                 62408
2CIDISCLIOFLT  I/Os in flight:                   0
2CIDISCLIOTK   I/O ticks (ms):                   100941
2CIDISCLLAVG   Weighted avg latency (us):        1082
NULL           ------------------------------------------------------------------------

[dev-koan]

FYI: @ymanton

[keithc-ca]

I think this change is good, but I'd like to see it squashed and also reviewed by the JIT team.

[mpirvu]

LGTM.
A couple of suggestions:

• If all disclaiming is disabled, disk stats are irrelevant and they should not be collected
• Disclaiming is only available on Linux. Should we print anything on all the other platforms?

[dev-koan]

LGTM. A couple of suggestions:

• If all disclaiming is disabled, disk stats are irrelevant and they should not be collected
• Disclaiming is only available on Linux. Should we print anything on all the other platforms?

• I am not collecting the disk stats anywhere but using an omr method call so it should be fine ...
• Yes the second point make sense, will update.

[mpirvu]

I am not collecting the disk stats anywhere but using an omr method call so it should be fine

Those omr methods internally open/scan/parse/close pseudo files. I'll let @ymanton comment on their overhead.

[dev-koan]

I am not collecting the disk stats anywhere but using an omr method call so it should be fine

Those omr methods internally open/scan/parse/close pseudo files. I'll let @ymanton comment on their overhead.

Ok makes sense, will update.

[ymanton]

Looks good so far, but it only covers a subset of the possible situations. The disclaimOnFile and disclaimOnSwap flags apply to the disclaimable memory areas that can be backed by a file or the swap, but they don't apply to the SCC, which is implicitly always backed by a file. We need to also get the device that the SCC file is on, and print the stats for that, but only if the device is different from the device we looked up for the other memory areas (otherwise info on the same device will be printed twice).

[dev-koan]

Will paste the new output.
Not sure if i could've used a helper method here to print the disk stats/

[keithc-ca]

Please fix the language in the commit message. Perhaps in "Added a struct a J9JITConfig" you meant "Added a struct to J9JITConfig"?

[dev-koan]

0SECTION       Memory disclaim info dump routine
NULL           ------------------------------------------------------------------------
1CIDISCLSUBS   Disclaim subsystem status
NULL           ------------------------------------------------------------------------
2CIDISCLDATA   Data cache disclaim:               enabled
2CIDISCLIPRO   IProfiler data disclaim:           enabled
2CIDISCLRTAM   Runtime assumption disclaim:       enabled
2CIDISCLCODE   Code cache disclaim:               disabled
2CIDISCLSCC    Shared class cache disclaim:       enabled
NULL           ------------------------------------------------------------------------
1CIDISCLBMED   Disclaim backing medium: swap
NULL           ------------------------------------------------------------------------
1CIDISCLDEV    Backing device I/O statistics
NULL           ------------------------------------------------------------------------
2CIDISCLDEVN   Device name:                       dm-0
2CIDISCLRDIO   Read I/Os:                         5741
2CIDISCLRDTK   Read ticks (ms):                   3209
2CIDISCLWRIO   Write I/Os:                        29948
2CIDISCLWRTK   Write ticks (ms):                  59359
2CIDISCLIOFLT  I/Os in flight:                    0
2CIDISCLIOTK   I/O ticks (ms):                    12384
2CIDISCLLAVG   Weighted average latency (us):     1462
NULL           ------------------------------------------------------------------------

[dev-koan]

^ is the latest output not sure if there should have been info printed regarding SCC device and disk stats separately. Ran it on x86 linux fyre vm.

[keithc-ca]

In the line

1CIDISCLBMED   Disclaim backing medium: swap

perhaps swap should line up with other values.