Simple process IO read/write rate limiter based on strace

0001-Strace-based-speed-limiter.patch

From 7959a97980894e1a47361e566d234a5f341dd05d Mon Sep 17 00:00:00 2001
From: Vitaly _Vi Shukela <vi0oss@gmail.com>
Date: Tue, 29 Nov 2011 19:29:50 +0300
Subject: [PATCH] Strace-based speed limiter

Apply to strace-4.6
Set env SPEEDLIMIT_READ=1000 and slow down other process with strace

Example: SPEEDLIMIT_READ=$((200*1024)) ./strace -o /dev/null -p `pidof wget`
---
 strace.c  |   11 +++++++++++
 syscall.c |   29 +++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+), 0 deletions(-)

diff --git a/strace.c b/strace.c
index 774d172..1ffb63b 100644
--- a/strace.c
+++ b/strace.c
@@ -199,6 +199,10 @@ usage: strace [-CdDffhiqrtttTvVxx] [-a column] [-e expr] ... [-o file]\n\
 " /* this is broken, so don't document it
 -z -- print only succeeding syscalls\n\
   */
+"Set SPEEDLIMIT_READ or SPEEDLIMIT_WRITE environment variables to\n\
+        bytes per seconds to slow down I/O of the traced process by\n\
+        sleeping after each successfull read/write-like syscall.\n\
+"
 , DEFAULT_ACOLUMN, DEFAULT_STRLEN, DEFAULT_SORTBY);
 	exit(exitval);
 }
@@ -914,6 +918,13 @@ main(int argc, char *argv[])
 		}
 	}
 
+    extern int speedlimit_read;
+    extern int speedlimit_write;
+    speedlimit_read=0;
+    speedlimit_write=0;
+    if(getenv("SPEEDLIMIT_READ")) sscanf(getenv("SPEEDLIMIT_READ"), "%i", &speedlimit_read);
+    if(getenv("SPEEDLIMIT_WRITE")) sscanf(getenv("SPEEDLIMIT_WRITE"), "%i", &speedlimit_write);
+
 	if ((optind == argc) == !pflag_seen)
 		usage(stderr, 1);
 
diff --git a/syscall.c b/syscall.c
index e66ac0a..7c2b369 100644
--- a/syscall.c
+++ b/syscall.c
@@ -168,6 +168,9 @@ static const int nerrnos2 = sizeof errnoent2 / sizeof errnoent2[0];
 const char *const *errnoent;
 int nerrnos;
 
+int speedlimit_read;
+int speedlimit_write;
+
 int current_personality;
 
 #ifndef PERSONALITY0_WORDSIZE
@@ -2556,6 +2559,32 @@ trace_syscall_exiting(struct tcb *tcp)
 	}
 	printtrailer();
 
+    if (sysent[tcp->scno].sys_func == sys_read ||
+		sysent[tcp->scno].sys_func == sys_pread ||
+		sysent[tcp->scno].sys_func == sys_pread64 ||
+		sysent[tcp->scno].sys_func == sys_recv ||
+		sysent[tcp->scno].sys_func == sys_recvfrom ||
+		sysent[tcp->scno].sys_func == sys_readv) {
+        
+        long long int ret = tcp->u_rval;
+        if (ret > 0 && speedlimit_read>0) {
+            usleep(ret * 1000000 / speedlimit_read);
+        }
+    } else
+    if (sysent[tcp->scno].sys_func == sys_write ||
+		sysent[tcp->scno].sys_func == sys_pwrite ||
+		sysent[tcp->scno].sys_func == sys_pwrite64 ||
+		sysent[tcp->scno].sys_func == sys_send ||
+		sysent[tcp->scno].sys_func == sys_sendto ||
+		sysent[tcp->scno].sys_func == sys_writev) {
+        
+        long long int ret = tcp->u_rval;
+        if (ret > 0 && speedlimit_write>0) {
+            usleep(ret * 1000000 / speedlimit_write);
+        }
+    }
+
+
 	dumpio(tcp);
 	if (fflush(tcp->outf) == EOF)
 		return -1;
-- 
1.7.6.4

Compiled version: http://vi-server.org/pub/strace_speedlimit