Messages in this thread Patch in this message | | | From | Omar Sandoval <> | Subject | [PATCH v3 7/8] proc/kcore: optimize multiple page reads | Date | Wed, 18 Jul 2018 15:58:47 -0700 |
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From: Omar Sandoval <osandov@fb.com>
The current code does a full search of the segment list every time for every page. This is wasteful, since it's almost certain that the next page will be in the same segment. Instead, check if the previous segment covers the current page before doing the list search.
Signed-off-by: Omar Sandoval <osandov@fb.com> --- fs/proc/kcore.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c index e2ca58d49938..25fefdd05ee5 100644 --- a/fs/proc/kcore.c +++ b/fs/proc/kcore.c @@ -428,10 +428,18 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen) tsz = buflen; + m = NULL; while (buflen) { - list_for_each_entry(m, &kclist_head, list) { - if (start >= m->addr && start < (m->addr+m->size)) - break; + /* + * If this is the first iteration or the address is not within + * the previous entry, search for a matching entry. + */ + if (!m || start < m->addr || start >= m->addr + m->size) { + list_for_each_entry(m, &kclist_head, list) { + if (start >= m->addr && + start < m->addr + m->size) + break; + } } if (&m->list == &kclist_head) { -- 2.18.0
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