[SERVER-16551] tcmalloc ReleaseToCentralCache account > 14% usage with long insert traffic Created: 15/Dec/14 Updated: 24/Jan/15 Resolved: 07/Jan/15 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | Performance, Storage |
| Affects Version/s: | 2.8.0-rc2 |
| Fix Version/s: | None |
| Type: | Bug | Priority: | Major - P3 |
| Reporter: | Rui Zhang (Inactive) | Assignee: | Geert Bosch |
| Resolution: | Won't Fix | Votes: | 0 |
| Labels: | 28qa | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Attachments: |
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| Backwards Compatibility: | Fully Compatible | ||||||||
| Operating System: | ALL | ||||||||
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| Description |
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during long insert with 64 threads, after about 2500 sec, perf event show tcmalloc's ReleaseToCentralCache is hot, sampled at 14.59% in the following case This test is done with wiredtiger, haven;t check mmapv1 yet.
it seems we can adjust max thread cache size to alleviate this situation. The default size is 32M per thread, did test with 64M, which seems improve the throughput
and here is perf even flame graph, you can check usage interactively. (please download and open in a new window for better view) |
| Comments |
| Comment by Githook User [ 13/Jan/15 ] |
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Author: {u'username': u'andy10gen', u'name': u'Andy Schwerin', u'email': u'schwerin@mongodb.com'}Message: Also, increases the default cap on the sum of all per-thread cache sizes from |
| Comment by Geert Bosch [ 07/Jan/15 ] |
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In the end, this is not performance-critical here, because the bottle-neck is in the journaling: less time in malloc would just mean more time in yield. As we're not going to change tcmalloc, I'm closing this. |