[C#] Added check for minimum page size to ensure it is at least of si…

…ze one sector (#380) * Added check for minimum page size to ensure it is at least of size one sector. * Update 23-fasterkv-tuning.md
microsoft · Nov 29, 2020 · 1c1e1a6 · 1c1e1a6
1 parent a27f0b5
commit 1c1e1a6
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Showing 5 changed files with 9 additions and 4 deletions.
diff --git a/cs/src/core/Allocator/AllocatorBase.cs b/cs/src/core/Allocator/AllocatorBase.cs
@@ -552,6 +552,10 @@ public AllocatorBase(LogSettings settings, IFasterEqualityComparer<Key> comparer
 
             device = settings.LogDevice;
             sectorSize = (int)device.SectorSize;
+
+            if (PageSize < sectorSize)
+                throw new FasterException($"Page size must be at least of device sector size ({sectorSize} bytes). Set PageSizeBits accordingly.");
+
             AlignedPageSizeBytes = ((PageSize + (sectorSize - 1)) & ~(sectorSize - 1));
         }
 

diff --git a/cs/test/BlittableIterationTests.cs b/cs/test/BlittableIterationTests.cs
@@ -25,7 +25,7 @@ public void Setup()
         {
             log = Devices.CreateLogDevice(TestContext.CurrentContext.TestDirectory + "/BlittableIterationTests.log", deleteOnClose: true);
             fht = new FasterKV<KeyStruct, ValueStruct>
-                (1L << 20, new LogSettings { LogDevice = log, MemorySizeBits = 15, PageSizeBits = 7 });
+                (1L << 20, new LogSettings { LogDevice = log, MemorySizeBits = 15, PageSizeBits = 9 });
         }
 
         [TearDown]

diff --git a/cs/test/BlittableLogCompactionTests.cs b/cs/test/BlittableLogCompactionTests.cs
@@ -25,7 +25,7 @@ public void Setup()
         {
             log = Devices.CreateLogDevice(TestContext.CurrentContext.TestDirectory + "/BlittableLogCompactionTests.log", deleteOnClose: true);
             fht = new FasterKV<KeyStruct, ValueStruct>
-                (1L << 20, new LogSettings { LogDevice = log, MemorySizeBits = 15, PageSizeBits = 7 });
+                (1L << 20, new LogSettings { LogDevice = log, MemorySizeBits = 15, PageSizeBits = 9 });
         }
 
         [TearDown]

diff --git a/cs/test/BlittableLogScanTests.cs b/cs/test/BlittableLogScanTests.cs
@@ -26,7 +26,7 @@ public void Setup()
         {
             log = Devices.CreateLogDevice(TestContext.CurrentContext.TestDirectory + "/BlittableFASTERScanTests.log", deleteOnClose: true);
             fht = new FasterKV<KeyStruct, ValueStruct>
-                (1L << 20, new LogSettings { LogDevice = log, MemorySizeBits = 15, PageSizeBits = 7 });
+                (1L << 20, new LogSettings { LogDevice = log, MemorySizeBits = 15, PageSizeBits = 9 });
         }
 
         [TearDown]

diff --git a/docs/_docs/23-fasterkv-tuning.md b/docs/_docs/23-fasterkv-tuning.md
@@ -36,7 +36,8 @@ the device via `IDisposable`.
 of bits. You get the actual size of the page by a simple computation of two raised to the power of the number
 specified (2<sup>P</sup>). For example, when `PageSizeBits` P is set to 12, it represents pages of size 4KB 
 (since 2<sup>P</sup> = 2<sup>10</sup> = 4096 = 4KB). Generally you should not need to adjust page size from its
-default value of 25 (= 32MB).
+default value of 25 (= 32MB). You cannot use a page size smaller than the device sector size (512 bytes by 
+default), which translates to a `PageSizeBits` value of at least 9.
 
 * `MemorySizeBits`: This field (M) indicates the total size of memory used by the log. As before, for a setting
 of M, 2<sup>M</sup> is the number of bytes used totally by the log. Since each page is of size 2<sup>P</sup>, the