[SERVER-4573] faults with every action Created: 28/Dec/11 Updated: 06/Apr/23 Resolved: 08/Feb/12 |
|
| Status: | Closed |
| Project: | Core Server |
| Component/s: | Testing Infrastructure |
| Affects Version/s: | 2.0.2 |
| Fix Version/s: | None |
| Type: | Question | Priority: | Minor - P4 |
| Reporter: | Brett Goldstein | Assignee: | Tad Marshall |
| Resolution: | Done | Votes: | 0 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Environment: |
RH Enterprise dual proc server |
||
| Participants: |
| Description |
|
Running a lab environment with approx 40 million documents. Watching mongostat, every action taken is incurring faults. What would be your recommended technique to identify the causality. |
| Comments |
| Comment by Tad Marshall [ 31/Jan/12 ] |
|
From the numbers in your mongostat output, it seems that your mapped dataset size (9.95 GB) is a lot larger than the amount that actually fits in memory (between 1.88 GB and 2.74 GB), so page faults will happen for every document that falls outside the resident memory. As expected, the fault rate is higher for inserts than for deletes (since a record to be deleted might be in memory, while an insert requires free space in a file region that probably won't be in memory if you are memory-constrained). Since you probably have no control over the locality of the data being removed or inserted, your best bet would be to increase RAM. |
| Comment by Eliot Horowitz (Inactive) [ 29/Dec/11 ] |
|
If the data set is a lot bigger than ram - than if operations are evenly distributed - most operations will produce a fault. |
| Comment by Brett Goldstein [ 29/Dec/11 ] |
|
this is from an insert job: [mongodb@my07apl01 ~]$ ./mongodb-linux-x86_64-2.0.2/bin/mongostat [mongodb@my07apl01 ~]$ |
| Comment by Brett Goldstein [ 29/Dec/11 ] |
|
This is from a large remove: [mongodb@my07apl01 ~]$ ./mongodb-linux-x86_64-2.0.2/bin/mongostat |
| Comment by Eliot Horowitz (Inactive) [ 28/Dec/11 ] |
|
Can you paste mongostat output? |