testcases: cve-2017-2671: Set attempts according to cpus

Message ID 20180713134618.29552-1-mylene.josserand@bootlin.com
State Superseded
Headers show
Series
  • testcases: cve-2017-2671: Set attempts according to cpus
Related show

Commit Message

Mylène Josserand July 13, 2018, 1:46 p.m.
This test tries to run commands with 0x8000 attempts.
In a slow system platform, it leads to a failure
because of a timeout even when it is configured with
LTP_TIMEOUT_MUL=10.

This commit adds a way to configure the number of attempts
according to the number of CPUs.
In case of 1 CPU and a slow platform, using 0x2000 attempts
with a LTP_TIMEOUT_MUL=3 make the test pass.

Signed-off-by: Mylène Josserand <mylene.josserand@bootlin.com>
---
 testcases/cve/cve-2017-2671.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

Comments

Richard Palethorpe July 16, 2018, 9:32 a.m. | #1
Hello,

Mylène Josserand writes:

> This test tries to run commands with 0x8000 attempts.
> In a slow system platform, it leads to a failure
> because of a timeout even when it is configured with
> LTP_TIMEOUT_MUL=10.
>
> This commit adds a way to configure the number of attempts
> according to the number of CPUs.
> In case of 1 CPU and a slow platform, using 0x2000 attempts
> with a LTP_TIMEOUT_MUL=3 make the test pass.

I think the Fuzzy Sync library needs to be improved to remove the
iteration constants altogether. That is, we specify how long the test(s)
should run for, not how many iterations each one should do.

We can do this by taking a moving average of the iteration time and
using it to predict when the next iteration will exceed the time
limit. Then exit the loop at that point.

Also Cyril thinks that we can improve the time Fuzzy Sync takes to reach
the synchronisation point by using a PID controller algorithm which
makes a lot of sense.

>
> Signed-off-by: Mylène Josserand <mylene.josserand@bootlin.com>
> ---
>  testcases/cve/cve-2017-2671.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/testcases/cve/cve-2017-2671.c b/testcases/cve/cve-2017-2671.c
> index b0471bfff..a56bb45a8 100644
> --- a/testcases/cve/cve-2017-2671.c
> +++ b/testcases/cve/cve-2017-2671.c
> @@ -49,7 +49,7 @@
>
>  #include "tst_fuzzy_sync.h"
>
> -#define ATTEMPTS 0x80000
> +#define ATTEMPTS 0x2000
>  #define PING_SYSCTL_PATH "/proc/sys/net/ipv4/ping_group_range"
>
>  static int sockfd;
> @@ -109,9 +109,13 @@ static void *connect_b(void * param LTP_ATTRIBUTE_UNUSED)
>
>  static void run(void)
>  {
> -	int i;
> +	int i, total_cpus;
>
> -	for (i = 0; i < ATTEMPTS; i++) {
> +	total_cpus = tst_ncpus();
> +	if (total_cpus > 4)
> +		total_cpus = 4;
> +
> +	for (i = 0; i < ATTEMPTS * total_cpus; i++) {
>  		SAFE_CONNECT(sockfd,
>  			     (struct sockaddr *)&iaddr, sizeof(iaddr));
>
> --
> 2.11.0


--
Thank you,
Richard.
Mylène Josserand July 23, 2018, 7:04 a.m. | #2
Hello,

Thank you for your review.

On Mon, 16 Jul 2018 11:32:08 +0200
Richard Palethorpe <rpalethorpe@suse.de> wrote:

> Hello,
> 
> Mylène Josserand writes:
> 
> > This test tries to run commands with 0x8000 attempts.
> > In a slow system platform, it leads to a failure
> > because of a timeout even when it is configured with
> > LTP_TIMEOUT_MUL=10.
> >
> > This commit adds a way to configure the number of attempts
> > according to the number of CPUs.
> > In case of 1 CPU and a slow platform, using 0x2000 attempts
> > with a LTP_TIMEOUT_MUL=3 make the test pass.  
> 
> I think the Fuzzy Sync library needs to be improved to remove the
> iteration constants altogether. That is, we specify how long the test(s)
> should run for, not how many iterations each one should do.

Okay, I will have a look at the Fuzzy Sync library because, honestly, I
have no idea what is it :)

> 
> We can do this by taking a moving average of the iteration time and
> using it to predict when the next iteration will exceed the time
> limit. Then exit the loop at that point.

okay, I see what you mean, thanks.

> 
> Also Cyril thinks that we can improve the time Fuzzy Sync takes to reach
> the synchronisation point by using a PID controller algorithm which
> makes a lot of sense.

Could you explain me more in details what you have in mind here?

Thank you in advance,
Best regards,

Mylène

> 
> >
> > Signed-off-by: Mylène Josserand <mylene.josserand@bootlin.com>
> > ---
> >  testcases/cve/cve-2017-2671.c | 10 +++++++---
> >  1 file changed, 7 insertions(+), 3 deletions(-)
> >
> > diff --git a/testcases/cve/cve-2017-2671.c b/testcases/cve/cve-2017-2671.c
> > index b0471bfff..a56bb45a8 100644
> > --- a/testcases/cve/cve-2017-2671.c
> > +++ b/testcases/cve/cve-2017-2671.c
> > @@ -49,7 +49,7 @@
> >
> >  #include "tst_fuzzy_sync.h"
> >
> > -#define ATTEMPTS 0x80000
> > +#define ATTEMPTS 0x2000
> >  #define PING_SYSCTL_PATH "/proc/sys/net/ipv4/ping_group_range"
> >
> >  static int sockfd;
> > @@ -109,9 +109,13 @@ static void *connect_b(void * param LTP_ATTRIBUTE_UNUSED)
> >
> >  static void run(void)
> >  {
> > -	int i;
> > +	int i, total_cpus;
> >
> > -	for (i = 0; i < ATTEMPTS; i++) {
> > +	total_cpus = tst_ncpus();
> > +	if (total_cpus > 4)
> > +		total_cpus = 4;
> > +
> > +	for (i = 0; i < ATTEMPTS * total_cpus; i++) {
> >  		SAFE_CONNECT(sockfd,
> >  			     (struct sockaddr *)&iaddr, sizeof(iaddr));
> >
> > --
> > 2.11.0  
> 
> 
> --
> Thank you,
> Richard.

Best regards,
Richard Palethorpe July 24, 2018, 8:12 a.m. | #3
Hello,

Mylène Josserand writes:

> Hello,
>
> Thank you for your review.
>
> On Mon, 16 Jul 2018 11:32:08 +0200
> Richard Palethorpe <rpalethorpe@suse.de> wrote:
>
>> Hello,
>>
>> Mylène Josserand writes:
>>
>> > This test tries to run commands with 0x8000 attempts.
>> > In a slow system platform, it leads to a failure
>> > because of a timeout even when it is configured with
>> > LTP_TIMEOUT_MUL=10.
>> >
>> > This commit adds a way to configure the number of attempts
>> > according to the number of CPUs.
>> > In case of 1 CPU and a slow platform, using 0x2000 attempts
>> > with a LTP_TIMEOUT_MUL=3 make the test pass.
>>
>> I think the Fuzzy Sync library needs to be improved to remove the
>> iteration constants altogether. That is, we specify how long the test(s)
>> should run for, not how many iterations each one should do.
>
> Okay, I will have a look at the Fuzzy Sync library because, honestly, I
> have no idea what is it :)
>
>>
>> We can do this by taking a moving average of the iteration time and
>> using it to predict when the next iteration will exceed the time
>> limit. Then exit the loop at that point.
>
> okay, I see what you mean, thanks.

Hopefully I should be able to implement something like this fairly
soon. However it would help if more people knew how the library works.

>
>>
>> Also Cyril thinks that we can improve the time Fuzzy Sync takes to reach
>> the synchronisation point by using a PID controller algorithm which
>> makes a lot of sense.
>
> Could you explain me more in details what you have in mind here?

We currently try to synchronise the execution of two functions by timing
how long it takes to reach each function. If one function is reached
quicker then we add or subtract a static number of cycles from a delay
loop. Eventually the delay loop should be sufficiently large to
synchronise the two functions.

To improve this we can use a PID algorithm
(https://en.wikipedia.org/wiki/PID_controller) to set the delay. I am
not exactly sure how we will implement that yet.

>
> Thank you in advance,
> Best regards,
>
> Mylène
>
>>
>> >
>> > Signed-off-by: Mylène Josserand <mylene.josserand@bootlin.com>
>> > ---
>> >  testcases/cve/cve-2017-2671.c | 10 +++++++---
>> >  1 file changed, 7 insertions(+), 3 deletions(-)
>> >
>> > diff --git a/testcases/cve/cve-2017-2671.c b/testcases/cve/cve-2017-2671.c
>> > index b0471bfff..a56bb45a8 100644
>> > --- a/testcases/cve/cve-2017-2671.c
>> > +++ b/testcases/cve/cve-2017-2671.c
>> > @@ -49,7 +49,7 @@
>> >
>> >  #include "tst_fuzzy_sync.h"
>> >
>> > -#define ATTEMPTS 0x80000
>> > +#define ATTEMPTS 0x2000
>> >  #define PING_SYSCTL_PATH "/proc/sys/net/ipv4/ping_group_range"
>> >
>> >  static int sockfd;
>> > @@ -109,9 +109,13 @@ static void *connect_b(void * param LTP_ATTRIBUTE_UNUSED)
>> >
>> >  static void run(void)
>> >  {
>> > -	int i;
>> > +	int i, total_cpus;
>> >
>> > -	for (i = 0; i < ATTEMPTS; i++) {
>> > +	total_cpus = tst_ncpus();
>> > +	if (total_cpus > 4)
>> > +		total_cpus = 4;
>> > +
>> > +	for (i = 0; i < ATTEMPTS * total_cpus; i++) {
>> >  		SAFE_CONNECT(sockfd,
>> >  			     (struct sockaddr *)nn&iaddr, sizeof(iaddr));
>> >
>> > --
>> > 2.11.0
>>
>>
>> --
>> Thank you,
>> Richard.
>
> Best regards,


--
Thank you,
Richard.

Patch

diff --git a/testcases/cve/cve-2017-2671.c b/testcases/cve/cve-2017-2671.c
index b0471bfff..a56bb45a8 100644
--- a/testcases/cve/cve-2017-2671.c
+++ b/testcases/cve/cve-2017-2671.c
@@ -49,7 +49,7 @@ 
 
 #include "tst_fuzzy_sync.h"
 
-#define ATTEMPTS 0x80000
+#define ATTEMPTS 0x2000
 #define PING_SYSCTL_PATH "/proc/sys/net/ipv4/ping_group_range"
 
 static int sockfd;
@@ -109,9 +109,13 @@  static void *connect_b(void * param LTP_ATTRIBUTE_UNUSED)
 
 static void run(void)
 {
-	int i;
+	int i, total_cpus;
 
-	for (i = 0; i < ATTEMPTS; i++) {
+	total_cpus = tst_ncpus();
+	if (total_cpus > 4)
+		total_cpus = 4;
+
+	for (i = 0; i < ATTEMPTS * total_cpus; i++) {
 		SAFE_CONNECT(sockfd,
 			     (struct sockaddr *)&iaddr, sizeof(iaddr));