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* Introduce write-mostly sumsAlexander Motin2021-05-271-0/+27
| | | | | | | | | | | | | | | | | | | | | wmsum counters are a reduced version of aggsum counters, optimized for write-mostly scenarios. They do not provide optimized read functions, but instead allow much cheaper add function. The primary usage is infrequently read statistic counters, not requiring exact precision. The Linux implementation is directly mapped into percpu_counter KPI. The FreeBSD implementation is directly mapped into counter(9) KPI. In user-space due to lack of better implementation mapped to aggsum. Unfortunately neither Linux percpu_counter nor FreeBSD counter(9) provide sufficient functionality to completelly replace aggsum, so it still remains to be used for several hot counters. Reviewed-by: Paul Dagnelie <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Ryan Moeller <[email protected]> Signed-off-by: Alexander Motin <[email protected]> Sponsored-By: iXsystems, Inc. Closes #12114
* Linux 5.10 compat: percpu_ref added data memberColeman Kane2020-11-021-0/+26
| | | | | | | | | | | | Kernel commit 2b0d3d3e4fcfb brought in some changes to the struct percpu_ref structure that moves most of its fields into a member struct named "data" of type struct percpu_ref_data. This includes the "count" member which is updated by vdev_blkg_tryget(), so update this function to chase the API change, and detect it via configure. Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Coleman Kane <[email protected]> Closes #11085
* Use percpu_counter for obj_alloc counter of Linux-backed cachesSerapheim Dimitropoulos2020-06-261-0/+34
A previous commit enabled the tracking of object allocations in Linux-backed caches from the SPL layer for debuggability. The commit is: 9a170fc6fe54f1e852b6c39630fe5ef2bbd97c16 Unfortunately, it also introduced minor performance regressions that were highlighted by the ZFS perf test-suite. Within Delphix we found that the regression would be from -1%, all the way up to -8% for some workloads. This commit brings performance back up to par by creating a separate counter for those caches and making it a percpu in order to avoid lock-contention. The initial performance testing was done by myself, and the final round was conducted by @tonynguien who was also the one that discovered the regression and highlighted the culprit. Reviewed-by: Matt Ahrens <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Serapheim Dimitropoulos <[email protected]> Closes #10397