|
|
| Line 273: |
Line 273: |
|
| |
|
| The sampling threshold can be adjusted with an option (see below). This will affect the precision of the output and the speed at which Firefox+DMD runs. | | The sampling threshold can be adjusted with an option (see below). This will affect the precision of the output and the speed at which Firefox+DMD runs. |
|
| |
| === Stack frame Records ===
| |
|
| |
| One shortcoming of stack trace records is that sometimes there are multiple stack trace records that have stacks that only vary by a small amount, and this can obscure the fact that a single function is ultimately responsible for all of the blocks covered by these heap allocations. Stack frame records are an attempt to identify such cases.
| |
|
| |
| Here's an example stack frame record from the "Unreported stack frame records" section:
| |
|
| |
| Unreported: ~4,047 blocks from ~979 strack trace records in stack frame record 39 of 11,482
| |
| ~16,634,045 bytes (~16,624,445 requested / ~9,600 slop)
| |
| 0.99% of the heap; 0.00% of unreported
| |
| PC is
| |
| PL_DHashTableInit (/home/njn/moz/mi2/dmdo64/xpcom/build/pldhash.cpp:231) 0x7f8451816018
| |
|
| |
| A stack frame record is a merging of every stack trace record that had an allocation stack trace containing its stack frame. In this example we can see that the initialization of pldhash structures (via pldhash.cpp:231) accounted for over 16 MiB of heap allocations, and those are spread over 4,047 heap blocks, which covered approximately 979 stack trace records.
| |
|
| |
|
| == Options == | | == Options == |