fscache: convert object to use workqueue instead of slow-work
Make fscache object state transition callbacks use workqueue instead
of slow-work. New dedicated unbound CPU workqueue fscache_object_wq
is created. get/put callbacks are renamed and modified to take
@object and called directly from the enqueue wrapper and the work
function. While at it, make all open coded instances of get/put to
use fscache_get/put_object().
* Unbound workqueue is used.
* work_busy() output is printed instead of slow-work flags in object
debugging outputs. They mean basically the same thing bit-for-bit.
* sysctl fscache.object_max_active added to control concurrency. The
default value is nr_cpus clamped between 4 and
WQ_UNBOUND_MAX_ACTIVE.
* slow_work_sleep_till_thread_needed() is replaced with fscache
private implementation fscache_object_sleep_till_congested() which
waits on fscache_object_wq congestion.
* debugfs support is dropped for now. Tracing API based debug
facility is planned to be added.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: David Howells <dhowells@redhat.com>
diff --git a/fs/fscache/main.c b/fs/fscache/main.c
index add6bdb..bb8d4c3 100644
--- a/fs/fscache/main.c
+++ b/fs/fscache/main.c
@@ -15,6 +15,7 @@
#include <linux/sched.h>
#include <linux/completion.h>
#include <linux/slab.h>
+#include <linux/seq_file.h>
#include "internal.h"
MODULE_DESCRIPTION("FS Cache Manager");
@@ -40,22 +41,89 @@
"FS-Cache debugging mask");
struct kobject *fscache_root;
+struct workqueue_struct *fscache_object_wq;
+
+DEFINE_PER_CPU(wait_queue_head_t, fscache_object_cong_wait);
+
+/* these values serve as lower bounds, will be adjusted in fscache_init() */
+static unsigned fscache_object_max_active = 4;
+
+#ifdef CONFIG_SYSCTL
+static struct ctl_table_header *fscache_sysctl_header;
+
+static int fscache_max_active_sysctl(struct ctl_table *table, int write,
+ void __user *buffer,
+ size_t *lenp, loff_t *ppos)
+{
+ struct workqueue_struct **wqp = table->extra1;
+ unsigned int *datap = table->data;
+ int ret;
+
+ ret = proc_dointvec(table, write, buffer, lenp, ppos);
+ if (ret == 0)
+ workqueue_set_max_active(*wqp, *datap);
+ return ret;
+}
+
+ctl_table fscache_sysctls[] = {
+ {
+ .procname = "object_max_active",
+ .data = &fscache_object_max_active,
+ .maxlen = sizeof(unsigned),
+ .mode = 0644,
+ .proc_handler = fscache_max_active_sysctl,
+ .extra1 = &fscache_object_wq,
+ },
+ {}
+};
+
+ctl_table fscache_sysctls_root[] = {
+ {
+ .procname = "fscache",
+ .mode = 0555,
+ .child = fscache_sysctls,
+ },
+ {}
+};
+#endif
/*
* initialise the fs caching module
*/
static int __init fscache_init(void)
{
+ unsigned int nr_cpus = num_possible_cpus();
+ unsigned int cpu;
int ret;
ret = slow_work_register_user(THIS_MODULE);
if (ret < 0)
goto error_slow_work;
+ fscache_object_max_active =
+ clamp_val(nr_cpus,
+ fscache_object_max_active, WQ_UNBOUND_MAX_ACTIVE);
+
+ ret = -ENOMEM;
+ fscache_object_wq = alloc_workqueue("fscache_object", WQ_UNBOUND,
+ fscache_object_max_active);
+ if (!fscache_object_wq)
+ goto error_object_wq;
+
+ for_each_possible_cpu(cpu)
+ init_waitqueue_head(&per_cpu(fscache_object_cong_wait, cpu));
+
ret = fscache_proc_init();
if (ret < 0)
goto error_proc;
+#ifdef CONFIG_SYSCTL
+ ret = -ENOMEM;
+ fscache_sysctl_header = register_sysctl_table(fscache_sysctls_root);
+ if (!fscache_sysctl_header)
+ goto error_sysctl;
+#endif
+
fscache_cookie_jar = kmem_cache_create("fscache_cookie_jar",
sizeof(struct fscache_cookie),
0,
@@ -78,8 +146,14 @@
error_kobj:
kmem_cache_destroy(fscache_cookie_jar);
error_cookie_jar:
+#ifdef CONFIG_SYSCTL
+ unregister_sysctl_table(fscache_sysctl_header);
+error_sysctl:
+#endif
fscache_proc_cleanup();
error_proc:
+ destroy_workqueue(fscache_object_wq);
+error_object_wq:
slow_work_unregister_user(THIS_MODULE);
error_slow_work:
return ret;
@@ -96,7 +170,9 @@
kobject_put(fscache_root);
kmem_cache_destroy(fscache_cookie_jar);
+ unregister_sysctl_table(fscache_sysctl_header);
fscache_proc_cleanup();
+ destroy_workqueue(fscache_object_wq);
slow_work_unregister_user(THIS_MODULE);
printk(KERN_NOTICE "FS-Cache: Unloaded\n");
}