Extend admission policies, statistics, add multi thread eviction and promotion

.github/workflows/build-cachelib-centos.yml → .github/workflows/build-cachelib-centos-long.yml

@@ -1,7 +1,8 @@
 name: build-cachelib-centos-latest
 on:
   schedule:
-     - cron:  '30 5 * * 1,4'
+    - cron:  '0 7 * * *'
+
 jobs:
   build-cachelib-centos8-latest:
     name: "CentOS/latest - Build CacheLib with all dependencies"
@@ -33,3 +34,6 @@ jobs:
         uses: actions/checkout@v2
       - name: "build CacheLib using build script"
         run: ./contrib/build.sh -j -v -T
+      - name: "run tests"
+        timeout-minutes: 60
+        run: cd opt/cachelib/tests && ../../../run_tests.sh long

.github/workflows/build-cachelib-debian.yml

@@ -1,7 +1,8 @@
 name: build-cachelib-debian-10
 on:
   schedule:
-     - cron:  '30 5 * * 2,6'
+    - cron:  '30 5 * * 0,3'
+
 jobs:
   build-cachelib-debian-10:
     name: "Debian/Buster - Build CacheLib with all dependencies"
@@ -37,3 +38,6 @@ jobs:
         uses: actions/checkout@v2
       - name: "build CacheLib using build script"
         run: ./contrib/build.sh -j -v -T
+      - name: "run tests"
+        timeout-minutes: 60
+        run: cd opt/cachelib/tests && ../../../run_tests.sh

.github/workflows/build-cachelib-docker.yml

@@ -0,0 +1,49 @@
+name: build-cachelib-docker
+on:
+  push:
+  pull_request:
+
+jobs:
+  build-cachelib-docker:
+    name: "CentOS/latest - Build CacheLib with all dependencies"
+    runs-on: ubuntu-latest
+    env:
+      REPO:           cachelib
+      GITHUB_REPO:    pmem/CacheLib
+      CONTAINER_REG:  ghcr.io/pmem/cachelib
+      CONTAINER_REG_USER:   ${{ secrets.GH_CR_USER }}
+      CONTAINER_REG_PASS:   ${{ secrets.GH_CR_PAT }}
+      FORCE_IMAGE_ACTION:   ${{ secrets.FORCE_IMAGE_ACTION }}
+      HOST_WORKDIR:         ${{ github.workspace }}
+      WORKDIR:              docker
+      IMG_VER:              devel
+    strategy:
+      matrix:
+        CONFIG: ["OS=centos OS_VER=8streams PUSH_IMAGE=1"]
+    steps:
+      - name: "System Information"
+        run: |
+          echo === uname ===
+          uname -a
+          echo === /etc/os-release ===
+          cat /etc/os-release
+          echo === df -hl ===
+          df -hl
+          echo === free -h ===
+          free -h
+          echo === top ===
+          top -b -n1 -1 -Eg || timeout 1 top -b -n1
+          echo === env ===
+          env
+          echo === gcc -v ===
+          gcc -v
+      - name: "checkout sources"
+        uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+
+      - name: Pull the image or rebuild and push it
+        run: cd $WORKDIR && ${{ matrix.CONFIG }} ./pull-or-rebuild-image.sh $FORCE_IMAGE_ACTION
+
+      - name: Run the build
+        run: cd $WORKDIR && ${{ matrix.CONFIG }} ./build.sh

.github/workflows/clang-format-check.yml

@@ -1,6 +1,6 @@
 # From: https://github.com/marketplace/actions/clang-format-check#multiple-paths
 name: clang-format Check
-on: [pull_request]
+on: []
 jobs:
   formatting-check:
     name: Formatting Check

MultiTierDataMovement.md

@@ -0,0 +1,117 @@
+# Background Data Movement
+
+In order to reduce the number of online evictions and support asynchronous
+promotion - we have added two periodic workers to handle eviction and promotion.
+
+The diagram below shows a simplified version of how the background evictor
+thread (green) is integrated to the CacheLib architecture. 
+
+<p align="center">
+  <img width="640" height="360" alt="BackgroundEvictor" src="cachelib-background-evictor.png">
+</p>
+
+## Synchronous Eviction and Promotion
+
+- `disableEvictionToMemory`: Disables eviction to memory (item is always evicted to NVMe or removed
+on eviction)
+
+## Background Evictors
+
+The background evictors scan each class to see if there are objects to move the next (lower)
+tier using a given strategy. Here we document the parameters for the different
+strategies and general parameters. 
+
+- `backgroundEvictorIntervalMilSec`: The interval that this thread runs for - by default
+the background evictor threads will wake up every 10 ms to scan the AllocationClasses. Also,
+the background evictor thead will be woken up everytime there is a failed allocation (from
+a request handling thread) and the current percentage of free memory for the 
+AllocationClass is lower than `lowEvictionAcWatermark`. This may render the interval parameter
+not as important when there are many allocations occuring from request handling threads. 
+
+- `evictorThreads`: The number of background evictors to run - each thread is a assigned
+a set of AllocationClasses to scan and evict objects from. Currently, each thread gets
+an equal number of classes to scan - but as object size distribution may be unequal - future
+versions will attempt to balance the classes among threads. The range is 1 to number of AllocationClasses.
+The default is 1. 
+
+- `maxEvictionBatch`: The number of objects to remove in a given eviction call. The
+default is 40. Lower range is 10 and the upper range is 1000. Too low and we might not
+remove objects at a reasonable rate, too high and it might increase contention with user threads.
+
+- `minEvictionBatch`: Minimum number of items to evict at any time (if there are any
+candidates)
+
+- `maxEvictionPromotionHotness`: Maximum candidates to consider for eviction. This is similar to `maxEvictionBatch`
+but it specifies how many candidates will be taken into consideration, not the actual number of items to evict.
+This option can be used to configure duration of critical section on LRU lock.
+
+
+### FreeThresholdStrategy (default)
+
+- `lowEvictionAcWatermark`: Triggers background eviction thread to run
+when this percentage of the AllocationClass is free. 
+The default is `2.0`, to avoid wasting capacity we don't set this above `10.0`.
+
+- `highEvictionAcWatermark`: Stop the evictions from an AllocationClass when this 
+percentage of the AllocationClass is free. The default is `5.0`, to avoid wasting capacity we
+don't set this above `10`.
+
+
+## Background Promoters
+
+The background promotes scan each class to see if there are objects to move to a lower
+tier using a given strategy. Here we document the parameters for the different
+strategies and general parameters.
+
+- `backgroundPromoterIntervalMilSec`: The interval that this thread runs for - by default
+the background promoter threads will wake up every 10 ms to scan the AllocationClasses for
+objects to promote.
+
+- `promoterThreads`: The number of background promoters to run - each thread is a assigned
+a set of AllocationClasses to scan and promote objects from. Currently, each thread gets
+an equal number of classes to scan - but as object size distribution may be unequal - future
+versions will attempt to balance the classes among threads. The range is `1` to number of AllocationClasses. The default is `1`.
+
+- `maxProtmotionBatch`: The number of objects to promote in a given promotion call. The
+default is 40. Lower range is 10 and the upper range is 1000. Too low and we might not
+remove objects at a reasonable rate, too high and it might increase contention with user threads. 
+
+- `minPromotionBatch`: Minimum number of items to promote at any time (if there are any
+candidates)
+
+- `numDuplicateElements`: This allows us to promote items that have existing handles (read-only) since
+we won't need to modify the data when a user is done with the data. Therefore, for a short time
+the data could reside in both tiers until it is evicted from its current tier. The default is to
+not allow this (0). Setting the value to 100 will enable duplicate elements in tiers.
+
+### Background Promotion Strategy (only one currently)
+
+- `promotionAcWatermark`: Promote items if there is at least this
+percent of free AllocationClasses. Promotion thread will attempt to move `maxPromotionBatch` number of objects
+to that tier. The objects are chosen from the head of the LRU. The default is `4.0`.
+This value should correlate with `lowEvictionAcWatermark`, `highEvictionAcWatermark`, `minAcAllocationWatermark`, `maxAcAllocationWatermark`.
+- `maxPromotionBatch`: The number of objects to promote in batch during BG promotion. Analogous to
+`maxEvictionBatch`. It's value should be lower to decrease contention on hot items.
+
+## Allocation policies
+
+- `maxAcAllocationWatermark`:  Item is always allocated in topmost tier if at least this 
+percentage of the AllocationClass is free.
+- `minAcAllocationWatermark`: Item is always allocated in bottom tier if only this percent
+of the AllocationClass is free. If percentage of free AllocationClasses is between `maxAcAllocationWatermark`
+and `minAcAllocationWatermark`: then extra checks (described below) are performed to decide where to put the element.
+
+By default, allocation will always be performed from the upper tier.
+
+- `acTopTierEvictionWatermark`: If there is less that this percent of free memory in topmost tier, cachelib will attempt to evict from top tier. This option takes precedence before allocationWatermarks.
+
+### Extra policies (used only when  percentage of free AllocationClasses is between `maxAcAllocationWatermark`
+and `minAcAllocationWatermark`)
+- `sizeThresholdPolicy`: If item is smaller than this value, always allocate it in upper tier.
+- `defaultTierChancePercentage`: Change (0-100%) of allocating item in top tier
+
+## MMContainer options
+
+- `lruInsertionPointSpec`: Can be set per tier when LRU2Q is used. Determines where new items are
+inserted. 0 = insert to hot queue, 1 = insert to warm queue, 2 = insert to cold queue
+- `markUsefulChance`: Per-tier, determines chance of moving item to the head of LRU on access