Dropping hugepages from the page cache relies on broken semantics in
2.6.20 and earlier kernels. Revert this commit as it is a no-op, now
that Ken Chen fixed those semantics. This does mean we'll use twice as
many hugepages for writable segments.
This reverts commit 76518908adaddc8de0638581243d5182514a595a.
---
elflink.c | 51 ---------------------------------------------------
1 files changed, 0 insertions(+), 51 deletions(-)
diff --git a/elflink.c b/elflink.c
index 03b79db..5058248 100644
--- a/elflink.c
+++ b/elflink.c
@@ -747,40 +747,6 @@ static int obtain_prepared_file(struct seg_info
*htlb_seg_info)
return 0;
}
-static void drop_cache(struct seg_info seg)
-{
- long hpage_size = gethugepagesize();
- void *p;
- char c;
-
- /*
- * take a COW fault on each hugepage in
- * the segment's file data ...
- */
- for (p = seg.vaddr; p <= seg.vaddr + seg.filesz;
- p += hpage_size) {
- memcpy(&c, p, 1);
- memcpy(p, &c, 1);
- }
- /*
- * ... as well as each huge page in the
- * extracopy area
- *
- */
- for (p = seg.extra_vaddr; p && p <= seg.extra_vaddr +
- seg.extrasz; p += hpage_size) {
- memcpy(&c, p, 1);
- memcpy(p, &c, 1);
- }
- /*
- * Note: fadvise() failing is not
- * actually an error, as we'll just use
- * an extra set of hugepages (in the
- * pagecache).
- */
- posix_fadvise(seg.fd, 0, 0, POSIX_FADV_DONTNEED);
-}
-
static void remap_segments(struct seg_info *seg, int num)
{
long hpage_size = gethugepagesize();
@@ -824,23 +790,6 @@ static void remap_segments(struct seg_info *seg, int num)
/* The segments are all back at this point.
* and it should be safe to reference static data
*/
-
- /*
- * This pagecache dropping code should not be used for shared segments.
- * But we currently only share read-only segments, so the below check
- * for PROT_WRITE is implicitly sufficient.
- *
- * Note: if minimal_copy is disabled, it is overkill to try and
- * save huge pages here by dropping them out of the cache, as we
- * will end up using more than normal anyways. Also, due to
- * limitations on certain architectures, we would need to avoid
- * prefaulting in the extracopy area so as to not use an
- * inordinate number of huge pages.
- */
- if (minimal_copy)
- for (i = 0; i < num; i++)
- if (seg[i].prot & PROT_WRITE)
- drop_cache(seg[i]);
}
static int check_env(void)
--
Nishanth Aravamudan <[EMAIL PROTECTED]>
IBM Linux Technology Center
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