diff options
Diffstat (limited to '0022-ZEN-INTERACTIVE-Enable-background-reclaim-of-hugepag.patch')
| -rw-r--r-- | 0022-ZEN-INTERACTIVE-Enable-background-reclaim-of-hugepag.patch | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/0022-ZEN-INTERACTIVE-Enable-background-reclaim-of-hugepag.patch b/0022-ZEN-INTERACTIVE-Enable-background-reclaim-of-hugepag.patch new file mode 100644 index 000000000000..fa1cba6a0238 --- /dev/null +++ b/0022-ZEN-INTERACTIVE-Enable-background-reclaim-of-hugepag.patch @@ -0,0 +1,66 @@ +From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 +From: "Jan Alexander Steffens (heftig)" <jan.steffens@gmail.com> +Date: Mon, 27 Jan 2020 18:21:09 +0100 +Subject: [PATCH] ZEN: INTERACTIVE: Enable background reclaim of hugepages + +Use [defer+madvise] as default khugepaged defrag strategy: + +For some reason, the default strategy to respond to THP fault fallbacks +is still just madvise, meaning stall if the program wants transparent +hugepages, but don't trigger a background reclaim / compaction if THP +begins to fail allocations. This creates a snowball affect where we +still use the THP code paths, but we almost always fail once a system +has been active and busy for a while. + +The option "defer" was created for interactive systems where THP can +still improve performance. If we have to fallback to a regular page due +to an allocation failure or anything else, we will trigger a background +reclaim and compaction so future THP attempts succeed and previous +attempts eventually have their smaller pages combined without stalling +running applications. + +We still want madvise to stall applications that explicitely want THP, +so defer+madvise _does_ make a ton of sense. Make it the default for +interactive systems, especially if the kernel maintainer left +transparent hugepages on "always". + +Reasoning and details in the original patch: https://lwn.net/Articles/711248/ +--- + init/Kconfig | 4 ++++ + mm/huge_memory.c | 4 ++++ + 2 files changed, 8 insertions(+) + +diff --git a/init/Kconfig b/init/Kconfig +index 450355b8aa2a..a77e78d1c9eb 100644 +--- a/init/Kconfig ++++ b/init/Kconfig +@@ -117,6 +117,10 @@ config ZEN_INTERACTIVE + + Default scheduler.........: mq-deadline -> bfq + ++ --- Virtual Memory Subsystem --------------------------- ++ ++ Background-reclaim hugepages...: no -> yes ++ + config BROKEN + bool + +diff --git a/mm/huge_memory.c b/mm/huge_memory.c +index 406a3c28c026..3538923b48ab 100644 +--- a/mm/huge_memory.c ++++ b/mm/huge_memory.c +@@ -54,7 +54,11 @@ unsigned long transparent_hugepage_flags __read_mostly = + #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE + (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| + #endif ++#ifdef CONFIG_ZEN_INTERACTIVE ++ (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG)| ++#else + (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)| ++#endif + (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)| + (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); + +-- +2.35.1 + |