return result;
}
-int osc_over_unstable_soft_limit(struct client_obd *cli)
-{
- long obd_upages, obd_dpages, osc_upages;
-
- /* Can't check cli->cl_unstable_count, therefore, no soft limit */
- if (!cli)
- return 0;
-
- obd_upages = atomic_read(&obd_unstable_pages);
- obd_dpages = atomic_read(&obd_dirty_pages);
-
- osc_upages = atomic_read(&cli->cl_unstable_count);
-
- /*
- * obd_max_dirty_pages is the max number of (dirty + unstable)
- * pages allowed at any given time. To simulate an unstable page
- * only limit, we subtract the current number of dirty pages
- * from this max. This difference is roughly the amount of pages
- * currently available for unstable pages. Thus, the soft limit
- * is half of that difference. Check osc_upages to ensure we don't
- * set SOFT_SYNC for OSCs without any outstanding unstable pages.
- */
- return osc_upages &&
- obd_upages >= (obd_max_dirty_pages - obd_dpages) / 2;
-}
-
/**
* Helper function called by osc_io_submit() for every page in an immediate
* transfer (i.e., transferred synchronously).
oap->oap_count = opg->ops_to - opg->ops_from;
oap->oap_brw_flags = brw_flags | OBD_BRW_SYNC;
- if (osc_over_unstable_soft_limit(oap->oap_cli))
- oap->oap_brw_flags |= OBD_BRW_SOFT_SYNC;
-
if (capable(CFS_CAP_SYS_RESOURCE)) {
oap->oap_brw_flags |= OBD_BRW_NOQUOTA;
oap->oap_cmd |= OBD_BRW_NOQUOTA;
}
}
+/**
+ * Check if a cl_page can be released, i.e, it's not being used.
+ *
+ * If unstable account is turned on, bulk transfer may hold one refcount
+ * for recovery so we need to check vmpage refcount as well; otherwise,
+ * even we can destroy cl_page but the corresponding vmpage can't be reused.
+ */
+static inline bool lru_page_busy(struct client_obd *cli, struct cl_page *page)
+{
+ if (cl_page_in_use_noref(page))
+ return true;
+
+ if (cli->cl_cache->ccc_unstable_check) {
+ struct page *vmpage = cl_page_vmpage(page);
+
+ /* vmpage have two known users: cl_page and VM page cache */
+ if (page_count(vmpage) - page_mapcount(vmpage) > 2)
+ return true;
+ }
+ return false;
+}
+
/**
* Drop @target of pages from LRU at most.
*/
break;
page = opg->ops_cl.cpl_page;
- if (cl_page_in_use_noref(page)) {
+ if (lru_page_busy(cli, page)) {
list_move_tail(&opg->ops_lru, &cli->cl_lru_list);
continue;
}
}
if (cl_page_own_try(env, io, page) == 0) {
- if (!cl_page_in_use_noref(page)) {
+ if (!lru_page_busy(cli, page)) {
/* remove it from lru list earlier to avoid
* lock contention
*/
return rc;
}
+/**
+ * osc_lru_reserve() is called to reserve an LRU slot for a cl_page.
+ *
+ * Usually the LRU slots are reserved in osc_io_iter_rw_init().
+ * Only in the case that the LRU slots are in extreme shortage, it should
+ * have reserved enough slots for an IO.
+ */
static int osc_lru_reserve(const struct lu_env *env, struct osc_object *obj,
struct osc_page *opg)
{
return rc;
}
+/**
+ * Atomic operations are expensive. We accumulate the accounting for the
+ * same page pgdat to get better performance.
+ * In practice this can work pretty good because the pages in the same RPC
+ * are likely from the same page zone.
+ */
+static inline void unstable_page_accounting(struct ptlrpc_bulk_desc *desc,
+ int factor)
+{
+ int page_count = desc->bd_iov_count;
+ pg_data_t *last = NULL;
+ int count = 0;
+ int i;
+
+ for (i = 0; i < page_count; i++) {
+ pg_data_t *pgdat = page_pgdat(desc->bd_iov[i].bv_page);
+
+ if (likely(pgdat == last)) {
+ ++count;
+ continue;
+ }
+
+ if (count > 0) {
+ mod_node_page_state(pgdat, NR_UNSTABLE_NFS,
+ factor * count);
+ count = 0;
+ }
+ last = pgdat;
+ ++count;
+ }
+ if (count > 0)
+ mod_node_page_state(last, NR_UNSTABLE_NFS, factor * count);
+}
+
+static inline void add_unstable_page_accounting(struct ptlrpc_bulk_desc *desc)
+{
+ unstable_page_accounting(desc, 1);
+}
+
+static inline void dec_unstable_page_accounting(struct ptlrpc_bulk_desc *desc)
+{
+ unstable_page_accounting(desc, -1);
+}
+
+/**
+ * Performs "unstable" page accounting. This function balances the
+ * increment operations performed in osc_inc_unstable_pages. It is
+ * registered as the RPC request callback, and is executed when the
+ * bulk RPC is committed on the server. Thus at this point, the pages
+ * involved in the bulk transfer are no longer considered unstable.
+ *
+ * If this function is called, the request should have been committed
+ * or req:rq_unstable must have been set; it implies that the unstable
+ * statistic have been added.
+ */
+void osc_dec_unstable_pages(struct ptlrpc_request *req)
+{
+ struct client_obd *cli = &req->rq_import->imp_obd->u.cli;
+ struct ptlrpc_bulk_desc *desc = req->rq_bulk;
+ int page_count = desc->bd_iov_count;
+ int unstable_count;
+
+ LASSERT(page_count >= 0);
+ dec_unstable_page_accounting(desc);
+
+ unstable_count = atomic_sub_return(page_count, &cli->cl_unstable_count);
+ LASSERT(unstable_count >= 0);
+
+ unstable_count = atomic_sub_return(page_count,
+ &cli->cl_cache->ccc_unstable_nr);
+ LASSERT(unstable_count >= 0);
+ if (!unstable_count)
+ wake_up_all(&cli->cl_cache->ccc_unstable_waitq);
+
+ if (osc_cache_too_much(cli))
+ (void)ptlrpcd_queue_work(cli->cl_lru_work);
+}
+
+/**
+ * "unstable" page accounting. See: osc_dec_unstable_pages.
+ */
+void osc_inc_unstable_pages(struct ptlrpc_request *req)
+{
+ struct client_obd *cli = &req->rq_import->imp_obd->u.cli;
+ struct ptlrpc_bulk_desc *desc = req->rq_bulk;
+ int page_count = desc->bd_iov_count;
+
+ /* No unstable page tracking */
+ if (!cli->cl_cache || !cli->cl_cache->ccc_unstable_check)
+ return;
+
+ add_unstable_page_accounting(desc);
+ atomic_add(page_count, &cli->cl_unstable_count);
+ atomic_add(page_count, &cli->cl_cache->ccc_unstable_nr);
+
+ /*
+ * If the request has already been committed (i.e. brw_commit
+ * called via rq_commit_cb), we need to undo the unstable page
+ * increments we just performed because rq_commit_cb wont be
+ * called again.
+ */
+ spin_lock(&req->rq_lock);
+ if (unlikely(req->rq_committed)) {
+ spin_unlock(&req->rq_lock);
+
+ osc_dec_unstable_pages(req);
+ } else {
+ req->rq_unstable = 1;
+ spin_unlock(&req->rq_lock);
+ }
+}
+
+/**
+ * Check if it piggybacks SOFT_SYNC flag to OST from this OSC.
+ * This function will be called by every BRW RPC so it's critical
+ * to make this function fast.
+ */
+bool osc_over_unstable_soft_limit(struct client_obd *cli)
+{
+ long unstable_nr, osc_unstable_count;
+
+ /* Can't check cli->cl_unstable_count, therefore, no soft limit */
+ if (!cli->cl_cache || !cli->cl_cache->ccc_unstable_check)
+ return false;
+
+ osc_unstable_count = atomic_read(&cli->cl_unstable_count);
+ unstable_nr = atomic_read(&cli->cl_cache->ccc_unstable_nr);
+
+ CDEBUG(D_CACHE,
+ "%s: cli: %p unstable pages: %lu, osc unstable pages: %lu\n",
+ cli->cl_import->imp_obd->obd_name, cli,
+ unstable_nr, osc_unstable_count);
+
+ /*
+ * If the LRU slots are in shortage - 25% remaining AND this OSC
+ * has one full RPC window of unstable pages, it's a good chance
+ * to piggyback a SOFT_SYNC flag.
+ * Please notice that the OST won't take immediate response for the
+ * SOFT_SYNC request so active OSCs will have more chance to carry
+ * the flag, this is reasonable.
+ */
+ return unstable_nr > cli->cl_cache->ccc_lru_max >> 2 &&
+ osc_unstable_count > cli->cl_max_pages_per_rpc *
+ cli->cl_max_rpcs_in_flight;
+}
+
/** @} osc */
projects / deliverable / linux.git / blobdiff