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authorJoerg Roedel <jroedel@suse.de>2020-03-22 04:22:41 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-04-02 17:34:20 +0300
commitc3cf92fd9b6352465edfa55c8968eca3cc766b93 (patch)
tree890134c4229a6427758ca3f3a48180db61010c08 /drivers/acpi
parenta07b91a7c51b5f701961900579e8653527ed1b1b (diff)
downloadlinux-c3cf92fd9b6352465edfa55c8968eca3cc766b93.tar.xz
x86/mm: split vmalloc_sync_all()
commit 763802b53a427ed3cbd419dbba255c414fdd9e7c upstream. Commit 3f8fd02b1bf1 ("mm/vmalloc: Sync unmappings in __purge_vmap_area_lazy()") introduced a call to vmalloc_sync_all() in the vunmap() code-path. While this change was necessary to maintain correctness on x86-32-pae kernels, it also adds additional cycles for architectures that don't need it. Specifically on x86-64 with CONFIG_VMAP_STACK=y some people reported severe performance regressions in micro-benchmarks because it now also calls the x86-64 implementation of vmalloc_sync_all() on vunmap(). But the vmalloc_sync_all() implementation on x86-64 is only needed for newly created mappings. To avoid the unnecessary work on x86-64 and to gain the performance back, split up vmalloc_sync_all() into two functions: * vmalloc_sync_mappings(), and * vmalloc_sync_unmappings() Most call-sites to vmalloc_sync_all() only care about new mappings being synchronized. The only exception is the new call-site added in the above mentioned commit. Shile Zhang directed us to a report of an 80% regression in reaim throughput. Fixes: 3f8fd02b1bf1 ("mm/vmalloc: Sync unmappings in __purge_vmap_area_lazy()") Reported-by: kernel test robot <oliver.sang@intel.com> Reported-by: Shile Zhang <shile.zhang@linux.alibaba.com> Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Borislav Petkov <bp@suse.de> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> [GHES] Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: <stable@vger.kernel.org> Link: http://lkml.kernel.org/r/20191009124418.8286-1-joro@8bytes.org Link: https://lists.01.org/hyperkitty/list/lkp@lists.01.org/thread/4D3JPPHBNOSPFK2KEPC6KGKS6J25AIDB/ Link: http://lkml.kernel.org/r/20191113095530.228959-1-shile.zhang@linux.alibaba.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/acpi')
-rw-r--r--drivers/acpi/apei/ghes.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index cd6fae6ad4c2..3f9f286088fa 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -201,7 +201,7 @@ static int ghes_estatus_pool_expand(unsigned long len)
* New allocation must be visible in all pgd before it can be found by
* an NMI allocating from the pool.
*/
- vmalloc_sync_all();
+ vmalloc_sync_mappings();
return gen_pool_add(ghes_estatus_pool, addr, PAGE_ALIGN(len), -1);
}