Small docs update

git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@589 d57e44dd-8a1f-0410-8b47-8ef2f437770f

scst/README

@@ -65,6 +65,10 @@ only adds one of those functions and nothing more. You may not patch the
 kernel if you don't need pass-through support or CONFIG_SCST_STRICT_SERIALIZING is
 defined during the compilation (see description below).
 
+Then, to get the maximum performance you should apply export_alloc_io_context
+patch. This patch simply makes alloc_io_context() function be available
+for modules, not only for built-in in kernel code.
+
 To compile SCST type 'make scst'. It will build SCST itself and its
 device handlers. To install them type 'make scst_install'. The driver
 modules will be installed in '/lib/modules/`you_kernel_version`/extra'.

scst/README_in-tree

@@ -671,11 +671,9 @@ using debug2perf Makefile target.
    directory, they also affect performance. If you find the best values,
    please share them with us.
 
- - On the target deadline IO scheduler with read_expire and
-   write_expire increased on all exported devices to 5000 and 15000
-   correspondingly should be the fastest for BLOCKIO, but for FILEIO
-   seems CFQ often outperforms it. So, try on your load and use the best
-   one.
+ - On the target CFQ IO scheduler. In most cases it has performance
+   advantage over other IO schedulers, sometimes huge (2+ times
+   aggregate throughput increase).
 
  - It is recommended to turn the kernel preemption off, i.e. set
    the kernel preemption model to "No Forced Preemption (Server)".

scst/src/scst_main.c

@@ -1693,6 +1693,14 @@ static int __init init_scst(void)
 	BUILD_BUG_ON(SCST_DATA_READ != DMA_FROM_DEVICE);
 	BUILD_BUG_ON(SCST_DATA_NONE != DMA_NONE);
 
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 25)
+#if !defined(SCST_ALLOC_IO_CONTEXT_EXPORTED)
+	PRINT_WARNING("%s", "Patch export_alloc_io_context was not applied on "
+		"your kernel. SCST will be working with not the best "
+		"performance."
+#endif
+#endif
+
 	mutex_init(&scst_mutex);
 	INIT_LIST_HEAD(&scst_template_list);
 	INIT_LIST_HEAD(&scst_dev_list);