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Date: Thu, 16 Oct 2008 01:06:50 -0500
From: Tom Zanussi <zanussi@...cast.net>
To: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Cc: Martin Bligh <mbligh@...gle.com>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
prasad@...ux.vnet.ibm.com,
Linus Torvalds <torvalds@...ux-foundation.org>,
Thomas Gleixner <tglx@...utronix.de>,
Mathieu Desnoyers <compudj@...stal.dyndns.org>,
Steven Rostedt <rostedt@...dmis.org>, od@...e.com,
"Frank Ch. Eigler" <fche@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>, hch@....de,
David Wilder <dwilder@...ibm.com>,
Jens Axboe <jens.axboe@...cle.com>,
Pekka Enberg <penberg@...helsinki.fi>,
Eduard - Gabriel Munteanu <eduard.munteanu@...ux360.ro>
Subject: [RFC PATCH 19/21] Add 'overwrite' mode back as 'flight' mode.
Uses per-cpu page pools as flight buffers, recycling pages and adding
pagewriter_save_flight_data() to dump it all to relay.
---
include/linux/relay_pagewriter.h | 3 ++
kernel/relay_pagewriter.c | 71 +++++++++++++++++++++++++++++++++++---
2 files changed, 69 insertions(+), 5 deletions(-)
diff --git a/include/linux/relay_pagewriter.h b/include/linux/relay_pagewriter.h
index 12378e5..91ad16b 100644
--- a/include/linux/relay_pagewriter.h
+++ b/include/linux/relay_pagewriter.h
@@ -25,6 +25,7 @@
* pagewriter flags
*/
#define PAGEWRITER_PAD_WRITES 0x00010000 /* don't cross pages */
+#define PAGEWRITER_FLIGHT_MODE 0x00020000 /* n_pages page ring */
/*
* Per-cpu pagewriter buffer
@@ -37,6 +38,7 @@ struct pagewriter_buf {
struct kref kref; /* channel buffer refcount */
struct list_head pool; /* current set of unused pages */
struct list_head empty_rpage_structs; /* cached rpage structs */
+ size_t n_pages_flight; /* number full flight pages written */
unsigned int cpu; /* this buf's cpu */
} ____cacheline_aligned;
@@ -283,5 +285,6 @@ extern struct pagewriter *pagewriter_open(const char *base_filename,
extern void pagewriter_flush(struct pagewriter *pagewriter);
extern void pagewriter_close(struct pagewriter *pagewriter);
extern void pagewriter_reset(struct pagewriter *pagewriter);
+extern void pagewriter_save_flight_data(struct pagewriter *pagewriter);
#endif /* _LINUX_RELAY_PAGEWRITER_H */
diff --git a/kernel/relay_pagewriter.c b/kernel/relay_pagewriter.c
index d27267f..9bc1461 100644
--- a/kernel/relay_pagewriter.c
+++ b/kernel/relay_pagewriter.c
@@ -41,6 +41,7 @@ static struct pagewriter_buf *pagewriter_open_buf(struct pagewriter *pw,
unsigned int cpu);
static void pagewriter_destroy(struct kref *kref);
static void __pagewriter_reset(struct pagewriter_buf *buf, unsigned int init);
+static void pagewriter_save_flight_buf(struct pagewriter_buf *buf);
/*
* pagewriter kernel API
@@ -201,6 +202,36 @@ void pagewriter_reset(struct pagewriter *pagewriter)
}
EXPORT_SYMBOL_GPL(pagewriter_reset);
+/**
+ * pagewriter_save_flight_data - log all pages dirtied in flight mode
+ * @pagewriter: pagewriter
+ *
+ * In flight mode (PAGEWRITER_FLIGHT_MODE), the pages written to
+ * via the pagewriter_write/reserve functions are simply cycled
+ * around the per-cpu page pools, and not sent to relay. This
+ * function provides a way, at the user's request, to simply
+ * sends all the dirty pages in the page pools to relay and
+ * therefore onto their final destination e.g. disk or network.
+ *
+ * The pagewriter and associated buffers will be in the same
+ * state as if hey were reset after this call.
+ */
+void pagewriter_save_flight_data(struct pagewriter *pagewriter)
+{
+ unsigned int i;
+
+ if (!pagewriter)
+ return;
+
+ mutex_lock(&pagewriters_mutex);
+ for_each_possible_cpu(i)
+ if (pagewriter->buf[i])
+ pagewriter_save_flight_buf(pagewriter->buf[i]);
+ relay_flush(pagewriter->rchan);
+ mutex_unlock(&pagewriters_mutex);
+}
+EXPORT_SYMBOL_GPL(pagewriter_save_flight_data);
+
/*
* end relay kernel API
*/
@@ -534,11 +565,15 @@ size_t pagewriter_switch_page_default_callback(struct pagewriter_buf *buf,
if (!(buf->pagewriter->flags & PAGEWRITER_PAD_WRITES))
remainder = length - (PAGE_SIZE - buf->offset);
- relay_add_page(buf->pagewriter->rchan, buf->page->page,
- &pagewriter_relay_page_callbacks, (void *)buf);
-
- buf->page->page = NULL;
- add_empty_rpage_struct(buf, buf->page);
+ if (buf->pagewriter->flags & PAGEWRITER_FLIGHT_MODE) {
+ list_add_tail(&buf->page->list, &buf->pool);
+ buf->n_pages_flight++;
+ } else {
+ relay_add_page(buf->pagewriter->rchan, buf->page->page,
+ &pagewriter_relay_page_callbacks, (void *)buf);
+ buf->page->page = NULL;
+ add_empty_rpage_struct(buf, buf->page);
+ }
buf->page = new_page;
buf->data = page_address(buf->page->page);
@@ -574,10 +609,36 @@ static void __pagewriter_reset(struct pagewriter_buf *buf, unsigned int init)
buf->page = pagewriter_get_free_page(buf);
buf->data = page_address(buf->page->page);
buf->offset = 0;
+ buf->n_pages_flight = 0;
buf->pagewriter->cb->new_page(buf, buf->data);
}
+static void pagewriter_save_flight_buf(struct pagewriter_buf *buf)
+{
+ size_t first_page, n_pages = buf->n_pages_flight;
+ struct relay_page *first_rpage;
+
+ buf->pagewriter->cb->switch_page(buf, 0, NULL);
+
+ if(buf->n_pages_flight > buf->pagewriter->n_pages)
+ n_pages = buf->pagewriter->n_pages;
+
+ first_page = buf->pagewriter->n_pages - n_pages;
+ list_for_each_entry(first_rpage, &buf->pool, list)
+ if (!first_page--)
+ break;
+
+ list_for_each_entry_from(first_rpage, &buf->pool, list) {
+ relay_add_page(buf->pagewriter->rchan, buf->page->page,
+ &pagewriter_relay_page_callbacks, (void *)buf);
+ buf->page->page = NULL;
+ add_empty_rpage_struct(buf, buf->page);
+ }
+
+ __pagewriter_reset(buf, 0);
+}
+
/**
* pagewriter_hotcpu_callback - CPU hotplug callback
* @nb: notifier block
--
1.5.3.5
--
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