From: Steinar H. Gunderson <sgunderson@bigfoot.com>
Date: Sat, 24 Nov 2018 10:17:12 +0000 (+0100)
Subject: Turn on MADV_RANDOM for Syzygy mmaps, so that the kernel may know it can reduce the... 
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=8c0a2733924f59316003c576ee2064ded490678b

Turn on MADV_RANDOM for Syzygy mmaps, so that the kernel may know it can reduce the readahead.
---

diff --git a/src/syzygy/tbprobe.cpp b/src/syzygy/tbprobe.cpp
index 8194f4b4..03cffca1 100644
--- a/src/syzygy/tbprobe.cpp
+++ b/src/syzygy/tbprobe.cpp
@@ -216,6 +216,7 @@ public:
         fstat(fd, &statbuf);
         *mapping = statbuf.st_size;
         *baseAddress = mmap(nullptr, statbuf.st_size, PROT_READ, MAP_SHARED, fd, 0);
+        madvise(*baseAddress, statbuf.st_size, MADV_RANDOM);
         ::close(fd);
 
         if (*baseAddress == MAP_FAILED) {