From: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Date: Mon, 26 Sep 2016 15:36:20 +0000 (+0900)
Subject: journald,ratelimit: fix wrong calculation of burst_modulate() (#4218)
X-Git-Tag: v232~187
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=eeb084806be1cc7f579d61634fe7b9b3dd5b3df9;p=thirdparty%2Fsystemd.git

journald,ratelimit: fix wrong calculation of burst_modulate() (#4218)

This patch fixes wrong calculation of burst_modulate(), which now calculates
the values smaller than really expected ones if available disk space is
strictly more than 1MB.

In particular, if available disk space is strictly more than 1MB and strictly
less than 16MB, the resulted value becomes smaller than its original one.

>>> (math.log2(1*1024**2)-16) / 4
1.0
>>> (math.log2(16*1024**2)-16) / 4
2.0
>>> (math.log2(256*1024**2)-16) / 4
3.0
→ This matches the comment in the function.
---

diff --git a/src/journal/journald-rate-limit.c b/src/journal/journald-rate-limit.c
index fce799a6ce0..d30bf92cec6 100644
--- a/src/journal/journald-rate-limit.c
+++ b/src/journal/journald-rate-limit.c
@@ -190,7 +190,7 @@ static unsigned burst_modulate(unsigned burst, uint64_t available) {
         if (k <= 20)
                 return burst;
 
-        burst = (burst * (k-20)) / 4;
+        burst = (burst * (k-16)) / 4;
 
         /*
          * Example: