1. 12 Feb, 2023 1 commit
    • Tian's avatar
      Reclaim page cache of RDB file (#11248) · 7dae142a
      Tian authored
      # Background
      The RDB file is usually generated and used once and seldom used again, but the content would reside in page cache until OS evicts it. A potential problem is that once the free memory exhausts, the OS have to reclaim some memory from page cache or swap anonymous page out, which may result in a jitters to the Redis service.
      
      Supposing an exact scenario, a high-capacity machine hosts many redis instances, and we're upgrading the Redis together. The page cache in host machine increases as RDBs are generated. Once the free memory drop into low watermark(which is more likely to happen in older Linux kernel like 3.10, before [watermark_scale_factor](https://lore.kernel.org/lkml/1455813719-2395-1-git-send-email-hannes@cmpxchg.org/) is introduced, the `low watermark` is linear to `min watermark`, and there'is not too much buffer space for `kswapd` to be wake up to reclaim memory), a `direct reclaim` happens, which means the process would stall to wait for memory allocation.
      
      # What the PR does
      The PR introduces a capability to reclaim the cache when the RDB is operated. Generally there're two cases, read and write the RDB. For read it's a little messy to address the incremental reclaim, so the reclaim is done in one go in background after the load is finished to avoid blocking the work thread. For write, incremental reclaim amortizes the work of reclaim so no need to put it into background, and the peak watermark of cache can be reduced in this way.
      
      Two cases are addresses specially, replication and restart, for both of which the cache is leveraged to speed up the processing, so the reclaim is postponed to a right time. To do this, a flag is added to`rdbSave` and `rdbLoad` to control whether the cache need to be kept, with the default value false.
      
      # Something deserve noting
      1. Though `posix_fadvise` is the POSIX standard, but only few platform support it, e.g. Linux, FreeBSD 10.0.
      2. In Linux `posix_fadvise` only take effect on writeback-ed pages, so a `sync`(or `fsync`, `fdatasync`) is needed to flush the dirty page before `posix_fadvise` if we reclaim write cache.
      
      # About test
      A unit test is added to verify the effect of `posix_fadvise`.
      In integration test overall cache increase is checked, as well as the cache backed by RDB as a specific TCL test is executed in isolated Github action job.
      7dae142a
  2. 26 Aug, 2022 1 commit
    • Moti Cohen's avatar
      Removing old redundant code from bio.c (#11136) · 246f44d7
      Moti Cohen authored
      * Remove redundant array bio_pending[]. Value at index i identically reflects the
      length of list bio_jobs[i]. Better use listLength() instead and discard this array.
      (no critical section issues to concern about).
      
      changed returned value of bioPendingJobsOfType() from "long long" to "long".
      
      Remove unused API. Maybe we will use this API later.
      246f44d7
  3. 25 Jul, 2022 1 commit
    • Binbin's avatar
      fsync the old aof file when open a new INCR AOF (#11004) · 03fff10a
      Binbin authored
      
      
      In rewriteAppendOnlyFileBackground, after flushAppendOnlyFile(1),
      and before openNewIncrAofForAppend, we should call redis_fsync
      to fsync the aof file.
      
      Because we may open a new INCR AOF in openNewIncrAofForAppend,
      in the case of using everysec policy, the old AOF file may not
      be fsynced in time (or even at all).
      
      When using everysec, we don't want to pay the disk latency from
      the main thread, so we will do a background fsync.
      
      Adding a argument for bioCreateCloseJob, a `need_fsync` flag to
      indicate that a fsync is required before the file is closed. So we will
      fsync the old AOF file before we close it.
      
      A cleanup, we make union become a union, since the free_* args and
      the fd / fsync args are never used together.
      Co-authored-by: default avatarOran Agra <oran@redislabs.com>
      03fff10a
  4. 29 Apr, 2021 1 commit
  5. 24 Dec, 2020 1 commit
  6. 21 Nov, 2019 1 commit
  7. 01 Oct, 2015 2 commits
  8. 27 Jul, 2015 1 commit
  9. 22 Nov, 2012 1 commit
    • antirez's avatar
      Make bio.c threads killable ASAP if needed. · 75369917
      antirez authored
      We use this new bio.c feature in order to stop our I/O threads if there
      is a memory test to do on crash. In this case we don't want anything
      else than the main thread to run, otherwise the other threads may mess
      with the heap and the memory test will report a false positive.
      75369917
  10. 08 Nov, 2012 1 commit
  11. 15 Sep, 2011 3 commits
  12. 13 Sep, 2011 1 commit