[src/trunk]: src/sys Rather than holding samples from each source until we ha...

[tls <tls%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/45fe8ba423c7
branches:  trunk
changeset: 784361:45fe8ba423c7
user:      tls <tls%NetBSD.org@localhost>
date:      Sat Jan 26 19:05:11 2013 +0000

description:
Rather than holding samples from each source until we have 64 at a time to
process, process them ASAP for low-rate sources, and for all sources if we
have not yet acquired initial entropy.

diffstat:

 sys/kern/kern_rndq.c |  46 +++++++++++++++++++++++++++++++++++-----------
 sys/sys/rnd.h        |   3 ++-
 2 files changed, 37 insertions(+), 12 deletions(-)

diffs (111 lines):

diff -r 73867ba19a62 -r 45fe8ba423c7 sys/kern/kern_rndq.c
--- a/sys/kern/kern_rndq.c      Sat Jan 26 18:44:21 2013 +0000
+++ b/sys/kern/kern_rndq.c      Sat Jan 26 19:05:11 2013 +0000
@@ -1,7 +1,7 @@
-/*     $NetBSD: kern_rndq.c,v 1.8 2013/01/24 14:23:45 riastradh Exp $  */
+/*     $NetBSD: kern_rndq.c,v 1.9 2013/01/26 19:05:12 tls Exp $        */
 
 /*-
- * Copyright (c) 1997-2011 The NetBSD Foundation, Inc.
+ * Copyright (c) 1997-2013 The NetBSD Foundation, Inc.
  * All rights reserved.
  *
  * This code is derived from software contributed to The NetBSD Foundation
@@ -32,7 +32,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_rndq.c,v 1.8 2013/01/24 14:23:45 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_rndq.c,v 1.9 2013/01/26 19:05:12 tls Exp $");
 
 #include <sys/param.h>
 #include <sys/ioctl.h>
@@ -80,12 +80,6 @@
 #endif
 
 /*
- * The size of a temporary buffer, kmem_alloc()ed when needed, and used for
- * reading and writing data.
- */
-#define        RND_TEMP_BUFFER_SIZE    128
-
-/*
  * This is a little bit of state information attached to each device that we
  * collect entropy from.  This is simply a collection buffer, and when it
  * is full it will be "detached" from the source and added to the entropy
@@ -665,6 +659,7 @@
        rnd_sample_t *state = NULL;
        const uint32_t *dint = data;
        int todo, done, filled = 0;
+       int sample_count;
        SIMPLEQ_HEAD(, _rnd_sample_t) tmp_samples =
                        SIMPLEQ_HEAD_INITIALIZER(tmp_samples);
 
@@ -672,11 +667,40 @@
                return;
        }
 
+       todo = len / sizeof(*dint);
+       /*
+        * Let's try to be efficient: if we are warm, and a source
+        * is adding entropy at a rate of at least 1 bit every 10 seconds,
+        * mark it as "fast" and add its samples in bulk.
+        */
+       if (__predict_true(rs->flags & RND_FLAG_FAST)) {
+               sample_count = RND_SAMPLE_COUNT;
+       } else {
+               if (!cold && rnd_initial_entropy) {
+                       struct timeval upt;
+
+                       getmicrouptime(&upt);
+                       if ((todo >= RND_SAMPLE_COUNT) ||
+                           (rs->total > upt.tv_sec) ||
+                            (upt.tv_sec > 10 &&
+                             rs->total > upt.tv_sec / 10)) {
+#ifdef RND_VERBOSE
+                               printf("rnd: source %s is fast (%d samples "
+                                      "at once, %d bits in %lld seconds), "
+                                      "processing samples in bulk.\n",
+                                      rs->name, todo, rs->total,
+                                      (long long int)upt.tv_sec);
+#endif
+                               rs->flags |= RND_FLAG_FAST;
+                       }
+               }
+               sample_count = 2;
+       }
+
        /*
         * Loop over data packaging it into sample buffers.
         * If a sample buffer allocation fails, drop all data.
         */
-       todo = len / sizeof(*dint);
        for (done = 0; done < todo ; done++) {
                state = rs->state;
                if (state == NULL) {
@@ -691,7 +715,7 @@
                state->values[state->cursor] = dint[done];
                state->cursor++;
 
-               if (state->cursor == RND_SAMPLE_COUNT) {
+               if (state->cursor == sample_count) {
                        SIMPLEQ_INSERT_HEAD(&tmp_samples, state, next);
                        filled++;
                        rs->state = NULL;
diff -r 73867ba19a62 -r 45fe8ba423c7 sys/sys/rnd.h
--- a/sys/sys/rnd.h     Sat Jan 26 18:44:21 2013 +0000
+++ b/sys/sys/rnd.h     Sat Jan 26 19:05:11 2013 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: rnd.h,v 1.34 2012/11/25 15:29:55 christos Exp $        */
+/*     $NetBSD: rnd.h,v 1.35 2013/01/26 19:05:11 tls Exp $     */
 
 /*-
  * Copyright (c) 1997 The NetBSD Foundation, Inc.
@@ -91,6 +91,7 @@
  */
 #define        RND_FLAG_NO_ESTIMATE    0x00000100      /* don't estimate entropy */
 #define        RND_FLAG_NO_COLLECT     0x00000200      /* don't collect entropy */
+#define RND_FLAG_FAST          0x00000400      /* process samples in bulk */
 
 #define        RND_TYPE_UNKNOWN        0       /* unknown source */
 #define        RND_TYPE_DISK           1       /* source is physical disk */