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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2013-05-24 12:30:03 +0200
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2013-06-26 21:10:03 +0200
commit25b41a7b67ee4f4d12cee8a4b8b5929e36c27e29 (patch)
tree519be1cacdb7a23ff314ade0cec813c6d59b1af9 /drivers/s390/char/sclp_con.c
parent92820a5f99748b02a3713a314d81e2fd0b6b2f80 (diff)
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s390/sclp: add parameter to specify number of buffer pages
Add a kernel parameter to be able to specify the number of pages to be used as output buffer by the line-mode sclp driver and the vt220 sclp driver. The current number of output pages is 6, if the service element is unavailable the boot messages alone can fill up the output buffer. If this happens the system blocks until the service element is working again. For a large LPAR with many devices it is sensible to have the ability to increase the output buffer size. To help to debug this situation add a counter for the page-pool-empty situation and make it available as a sclp driver attribute. To avoid the system to stall until the service element works again add another kernel parameter to allow to drop output buffers. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'drivers/s390/char/sclp_con.c')
-rw-r--r--drivers/s390/char/sclp_con.c31
1 files changed, 30 insertions, 1 deletions
diff --git a/drivers/s390/char/sclp_con.c b/drivers/s390/char/sclp_con.c
index ecf45c54f8c4..5880def98fc1 100644
--- a/drivers/s390/char/sclp_con.c
+++ b/drivers/s390/char/sclp_con.c
@@ -130,6 +130,31 @@ sclp_console_timeout(unsigned long data)
}
/*
+ * Drop oldest console buffer if sclp_con_drop is set
+ */
+static int
+sclp_console_drop_buffer(void)
+{
+ struct list_head *list;
+ struct sclp_buffer *buffer;
+ void *page;
+
+ if (!sclp_console_drop)
+ return 0;
+ list = sclp_con_outqueue.next;
+ if (sclp_con_queue_running)
+ /* The first element is in I/O */
+ list = list->next;
+ if (list == &sclp_con_outqueue)
+ return 0;
+ list_del(list);
+ buffer = list_entry(list, struct sclp_buffer, list);
+ page = sclp_unmake_buffer(buffer);
+ list_add_tail((struct list_head *) page, &sclp_con_pages);
+ return 1;
+}
+
+/*
* Writes the given message to S390 system console
*/
static void
@@ -150,9 +175,13 @@ sclp_console_write(struct console *console, const char *message,
do {
/* make sure we have a console output buffer */
if (sclp_conbuf == NULL) {
+ if (list_empty(&sclp_con_pages))
+ sclp_console_full++;
while (list_empty(&sclp_con_pages)) {
if (sclp_con_suspended)
goto out;
+ if (sclp_console_drop_buffer())
+ break;
spin_unlock_irqrestore(&sclp_con_lock, flags);
sclp_sync_wait();
spin_lock_irqsave(&sclp_con_lock, flags);
@@ -297,7 +326,7 @@ sclp_console_init(void)
return rc;
/* Allocate pages for output buffering */
INIT_LIST_HEAD(&sclp_con_pages);
- for (i = 0; i < MAX_CONSOLE_PAGES; i++) {
+ for (i = 0; i < sclp_console_pages; i++) {
page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
list_add_tail(page, &sclp_con_pages);
}