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authorDave Hansen <dave.hansen@linux.intel.com>2014-07-31 19:41:01 +0400
committerH. Peter Anvin <hpa@linux.intel.com>2014-07-31 19:48:51 +0400
commit2d040a1ce903ca5d6e7c983621fb29c6883c4c48 (patch)
tree2969f9de20422d8e247cf6e13d043330878baff6 /arch/x86/mm
parentd17d8f9dedb9dd76fd540a5c497101529d9eb25a (diff)
downloadlinux-2d040a1ce903ca5d6e7c983621fb29c6883c4c48.tar.xz
x86/mm: New tunable for single vs full TLB flush
Most of the logic here is in the documentation file. Please take a look at it. I know we've come full-circle here back to a tunable, but this new one is *WAY* simpler. I challenge anyone to describe in one sentence how the old one worked. Here's the way the new one works: If we are flushing more pages than the ceiling, we use the full flush, otherwise we use per-page flushes. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Link: http://lkml.kernel.org/r/20140731154101.12B52CAF@viggo.jf.intel.com Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/mm')
-rw-r--r--arch/x86/mm/tlb.c46
1 files changed, 46 insertions, 0 deletions
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 6f00ecb9feeb..cb7caddf0902 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -265,3 +265,49 @@ void flush_tlb_kernel_range(unsigned long start, unsigned long end)
on_each_cpu(do_kernel_range_flush, &info, 1);
}
}
+
+static ssize_t tlbflush_read_file(struct file *file, char __user *user_buf,
+ size_t count, loff_t *ppos)
+{
+ char buf[32];
+ unsigned int len;
+
+ len = sprintf(buf, "%ld\n", tlb_single_page_flush_ceiling);
+ return simple_read_from_buffer(user_buf, count, ppos, buf, len);
+}
+
+static ssize_t tlbflush_write_file(struct file *file,
+ const char __user *user_buf, size_t count, loff_t *ppos)
+{
+ char buf[32];
+ ssize_t len;
+ int ceiling;
+
+ len = min(count, sizeof(buf) - 1);
+ if (copy_from_user(buf, user_buf, len))
+ return -EFAULT;
+
+ buf[len] = '\0';
+ if (kstrtoint(buf, 0, &ceiling))
+ return -EINVAL;
+
+ if (ceiling < 0)
+ return -EINVAL;
+
+ tlb_single_page_flush_ceiling = ceiling;
+ return count;
+}
+
+static const struct file_operations fops_tlbflush = {
+ .read = tlbflush_read_file,
+ .write = tlbflush_write_file,
+ .llseek = default_llseek,
+};
+
+static int __init create_tlb_single_page_flush_ceiling(void)
+{
+ debugfs_create_file("tlb_single_page_flush_ceiling", S_IRUSR | S_IWUSR,
+ arch_debugfs_dir, NULL, &fops_tlbflush);
+ return 0;
+}
+late_initcall(create_tlb_single_page_flush_ceiling);