From: Rick Edgecombe <rick.p.edgecombe@intel.com>
To: akpm@linux-foundation.org, linux-mm@kvack.org,
bpf@vger.kernel.org, dave.hansen@linux.intel.com,
peterz@infradead.org, luto@kernel.org, jeyu@kernel.org
Cc: linux-kernel@vger.kernel.org, ast@kernel.org,
daniel@iogearbox.net, andrii@kernel.org, hch@infradead.org,
x86@kernel.org, Rick Edgecombe <rick.p.edgecombe@intel.com>
Subject: [RFC 0/3] Group pages on the direct map for permissioned vmallocs
Date: Mon, 5 Apr 2021 13:37:08 -0700 [thread overview]
Message-ID: <20210405203711.1095940-1-rick.p.edgecombe@intel.com> (raw)
Hi,
This is a followup to the previous attempt to overhaul how vmalloc permissions
are done:
https://lore.kernel.org/lkml/20201120202426.18009-1-rick.p.edgecombe@intel.com/
In working on a next version it dawned on me that we can significantly reduce
direct map breakage on x86 with a much less invasive change, so I thought maybe
I would start there in the meantime.
In a test of booting fedora and running the BPF unit tests, this reduced 4k
direct map pages by 98%.
It simply uses pages for x86 module_alloc() mappings from a cache created out of
2MB pages. This results in all the later breakage clustering in 2MB blocks on
the direct map. The trade-off is colder pages are used for these allocations.
All module_alloc() users (modules, ebpf jit, ftrace, kprobes) get this behavior.
Potentially this behavior should be enabled for eBPF byte code allocations as
well in the case of !CONFIG_BPF_JIT_ALWAYS_ON.
The new APIs and invasive changes in the callers can happen after vmalloc huge
pages bring more benefits. Although, I can post shootdown reduction changes with
previous comments integrated if anyone disagrees.
Based on v5.11.
Thanks,
Rick
Rick Edgecombe (3):
list: Support getting most recent element in list_lru
vmalloc: Support grouped page allocations
x86/module: Use VM_GROUP_PAGES flag
arch/x86/Kconfig | 1 +
arch/x86/kernel/module.c | 2 +-
include/linux/list_lru.h | 13 +++
include/linux/vmalloc.h | 1 +
mm/Kconfig | 9 ++
mm/list_lru.c | 28 +++++
mm/vmalloc.c | 215 +++++++++++++++++++++++++++++++++++++--
7 files changed, 257 insertions(+), 12 deletions(-)
--
2.29.2
next reply other threads:[~2021-04-05 20:41 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-05 20:37 Rick Edgecombe [this message]
2021-04-05 20:37 ` [RFC 1/3] list: Support getting most recent element in list_lru Rick Edgecombe
2021-04-05 20:37 ` [RFC 2/3] vmalloc: Support grouped page allocations Rick Edgecombe
2021-04-05 21:01 ` Dave Hansen
2021-04-05 21:32 ` Matthew Wilcox
2021-04-05 21:49 ` Edgecombe, Rick P
2021-04-05 21:38 ` Edgecombe, Rick P
2021-04-05 20:37 ` [RFC 3/3] x86/module: Use VM_GROUP_PAGES flag Rick Edgecombe
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