Re: [ccache] ccacje direct mode without fall back to running the preprocessor
Hello Andew, > The answer is "no", because it is necessary to run the preprocessor in order to fill the cache and record the file list that direct mode lookups use. What are the consequences if we don't let ccache record the file list, but just run the preprocessor and do a cache lookup using the preprocessor mode? WiIl I just have additional overhead when the next direct-look up runs? I guess this is the only drawback. regards, Venkat. On Fri, Sep 5, 2014 at 1:51 AM, Andrew Stubbs <a...@codesourcery.com> wrote: > On 04/09/14 08:32, vkr wrote:> I would like to know if I can avoid > > "If there is no match, ccache falls back to running the preprocessor." > > The answer is "no", because it is necessary to run the preprocessor in > order to fill the cache and record the file list that direct mode lookups > use. > > It might be possible if you wanted to run the cache in read-only mode, but > that might not be very useful, and I don't believe there's an option for > that now. > > Andrew > ___ ccache mailing list ccache@lists.samba.org https://lists.samba.org/mailman/listinfo/ccache
[ccache] Implementing a Read-only HTTP CCACHE_DIR(resurrect)
Hello, I stumbled across this thread - https://lists.samba.org/archive/ccache/2012q2/000879.html which is years old, Coincidentally, I did some work along similar lines already, without realizing there was this discussion about this topic here, and I appreciate some comments/suggestions on my approach so far. Having cache on NFS is comparatively the easy option from configuration point of view, however, there can be environments where for whatever the reasons, NFS server is a few hops away, while there are other machines that are closer to the build farm, in which case, having a HTTP CCACHE_DIR does seemed like a reasonably better option as it involves less configuration havoc on every machine in the build farm. Keeping the above as use case, I've implemented HTTP CCACHE_DIR in my fork - https://github.com/venkrao/ccache This is a very crude throw-away test from a beginner C Programmer, that does the following. Care has been taken to ensure it does behave like existing ccache to the extent I know so far, and I did have successful runs of modified ccache with no core/crash or surprise failures. 1. Offers ONLY read-only http ccache_dir! 2. A Server process is to be started on the build machine(as of now, independent of ccache. But plan is to integrate this into ccache)(see server.c in the fork) 3. Server process uses a single cURL handle, and listens to all the incoming cache download requests(which can be for .d/.o/.manifest or any such file that ccache looks up otherwise in the CCACHE_DIR location) 4. Server process was necessary to share the cURL handle, to reuse a single http connection as much as possible(have I got it right that this does save some overhead on cURL that not many tcp connections are opened by cURL?) 5. ccache sends the URL, and the download location to the server, and it gets a response code based on which ccache runs the next actions. Unfortunately, in our existing environment I could not see visible improvement between our NFS based cache setup and this new approach. I cannot attribute the lack of performance to anything right now. I do think that http ccache_dir is better than NFS based cache in our case because, by benchmarking for data copy say so. Example, specific amount of data copied between my webserver(used in the new approach tests), and the build machine as compared to NFS server and build machine shows NFS is no good for us. In simple terms, is it a viable feature that my fork may be integrated into ccache after careful consideration, that ccache_dir is served via http?(for both get, and put cache) Please consider reviewing the changes I made. Your comments and time are greatly appreciated. Regards, Venkat. ___ ccache mailing list ccache@lists.samba.org https://lists.samba.org/mailman/listinfo/ccache
[ccache] @file arguments to ccache - Intel Compiler
Hello, I was wondering why in ccache we are expanding @file https://github.com/venkrao/ccache-1/blob/59e5244dd79b0fc7df682c8f3c05b778a3d00f91/ccache.c#L1951 Essentially, the arguments that are to be listed in @file are those that affect the preprocessor. Is it safe to just not expand the arguments onto the commandline via ccache function above, but, just pass on the @file argument as-is to the compiler command-line? The reason I'm asking this is, Intel compiler, apparently accepts shell comments(# comments) inside the .cfg file, as well as new line characters. And as far as my test results reveal, those fail ccache, as we do not care filtering our the shell comments inside ccache, instead, read the entire file content and put it into the command-line, and this results in "Preprocessor error" So, is it safe to just pass on the @file as-is to compiler, without letting ccache read and expand the arguments? I can think of a bad case, where the user puts in an absolute path -I path inside the @file, and that results in cache miss in direct mode.. I'm unable to decide how to go about supporting Intel compiler, especially with the @file. Intel compiler apparently even accepts special char like hello.h$ or regex based input args inside the @file which might make ccache handle them more difficult. Regards, Venkat. ___ ccache mailing list ccache@lists.samba.org https://lists.samba.org/mailman/listinfo/ccache
Re: [ccache] ccacje direct mode without fall back to running the preprocessor
Hello. Sure, that name is an apt one and I'm glad saved a few seconds :) Regards, venkrao On Tue, Sep 16, 2014 at 12:54 AM, Joel Rosdahl j...@rosdahl.net wrote: Hi, I'm not opposed to introducing such an option. What would be a good name? CCACHE_READONLY_DIRECT (readonly_direct in the config file on master)? -- Joel On 10 September 2014 09:57, Andrew Stubbs a...@codesourcery.com wrote: On 10/09/14 08:24, vkr wrote: Why is that? I mean, when drop preprocessing only when an env variable is set, why is it not the right approach? The development sources on the master branch has all-new option and environment variable processing code. The part where you act on the option is probably in the right place, but it ought to be read elsewhere. I'm not sure how that worked in 3.1.9. Andrew ___ ccache mailing list ccache@lists.samba.org https://lists.samba.org/mailman/listinfo/ccache ___ ccache mailing list ccache@lists.samba.org https://lists.samba.org/mailman/listinfo/ccache
Re: [ccache] ccacje direct mode without fall back to running the preprocessor
Hi Andrew, It's not the right implementation for the master branch, but might be ok in the release branch? Why is that? I mean, when drop preprocessing only when an env variable is set, why is it not the right approach? Regards, Venkrao On Mon, Sep 8, 2014 at 4:32 PM, Andrew Stubbs a...@codesourcery.com wrote: On 08/09/14 11:37, vkr wrote: If the env variable TRS_CCACHE_NO_PREPROCESSOR_ON_DIRECT_LOOKUP_MISS is set then, I do not run preprocessing, but just fall back to running real-compiler. I see a lot of time saving, and I can't think of any side-effect. It's not the right implementation for the master branch, but might be ok in the release branch? That's up to Joel. Seems like a worthwhile feature, in read-only mode. Andrew ___ ccache mailing list ccache@lists.samba.org https://lists.samba.org/mailman/listinfo/ccache
Re: [ccache] ccacje direct mode without fall back to running the preprocessor
Hi Andrew
It seems to me that I can switch off preprocessing in a read-only
ccache mode, after a direct lookup fail.
How do you see the following patch?
If the env variable TRS_CCACHE_NO_PREPROCESSOR_ON_DIRECT_LOOKUP_MISS is set
then, I do not run preprocessing, but just fall back to running real-compiler.
I see a lot of time saving, and I can't think of any side-effect.
Your comments on this are very much appreciated. Thank you!.
--- ccache-3.1.9/ccache.c 2013-01-06 22:27:59.0 +0530
+++ ccache-3.1.9_patched/ccache.c 2014-09-08 15:55:49.0 +0530
@@ -2029,6 +2029,14 @@
}
}
+
+ if (getenv(CCACHE_READONLY)) {
+ if (getenv(TRS_CCACHE_NO_PREPROCESSOR_ON_DIRECT_LOOKUP_MISS)) {
+ cc_log(TRS; Lets no run preprocessor in read-only mode, as it
goes in vain. Running real-compiler.);
+ failed();
+ }
+ }
+
/*
* Find the hash using the preprocessed output. Also updates
* included_files.
On Fri, Sep 5, 2014 at 2:51 PM, vkr venkatakrishnarao...@gmail.com wrote:
Hello
First of all, sorry about the typo in the subject/title of my post.
I run ccache in read-only mode itself. But, I still see that after the
direct cache lookup fail, it falls back to running the preprocessor.
That's exactly what I wanted to avoid.
It seems to me that having an option to avoid preprocessing after a
direct-cache-lookup fail is still a very valid option if the user
knows that preprocesor will result in a failure/he purposefully wants
to avoid it.
I hope my justification is valid.
88 [2014-09-05T14:45:17.445383 25208] Hostname: host.myhost.net
89 [2014-09-05T14:45:17.445393 25208] Working directory: (null)
90 [2014-09-05T14:45:17.445399 25208] Base directory:
/var/fpwork/workspace_venkrao/release
91 [2014-09-05T14:45:17.445734 25208] Source file: ../my_source.cpp
92 [2014-09-05T14:45:17.445745 25208] Dependency file: ../my_source.d
93 [2014-09-05T14:45:17.445752 25208] Object file: ../my_source.cpp.o
94 [2014-09-05T14:45:17.447011 25208] Trying direct lookup
95 [2014-09-05T14:45:17.447167 25208] Looking for object file hash in
/disk1/ccache_cache_store/transport_release/175750/0/5/eb2b36e5e9d0bb723de833a4529cab-11859.manifest
96 [2014-09-05T14:45:17.479757 25204] Looking for object file hash in
/disk1/ccache_cache_store/transport_release/175750/6/6/e186baaf3c2e9e06619878dac77fe1-114310.manifest
97 [2014-09-05T14:45:17.863524 25194] Did not find object file hash in
manifest
98 [2014-09-05T14:45:17.864854 25194] Running preprocessor
Regards,
venkrao
On Fri, Sep 5, 2014 at 1:51 AM, Andrew Stubbs a...@codesourcery.com wrote:
On 04/09/14 08:32, vkr wrote: I would like to know if I can avoid
If there is no match, ccache falls back to running the preprocessor.
The answer is no, because it is necessary to run the preprocessor in order
to fill the cache and record the file list that direct mode lookups use.
It might be possible if you wanted to run the cache in read-only mode, but
that might not be very useful, and I don't believe there's an option for
that now.
Andrew
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[ccache] ccacje direct mode without fall back to running the preprocessor
Hello The documentation about direct mode says: The current contents of the include files are then hashed and compared to the information in the manifest. If there is a match, ccache knows the result of the compilation. If there is no match, ccache falls back to running the preprocessor. The output from the preprocessor is parsed to find the include files that were read. The paths and hash sums of those include files are then stored in the manifest along with information about the produced compilation result. I would like to know if I can avoid If there is no match, ccache falls back to running the preprocessor. The reason is if I know that cache lookup with preprocessor output will also result in a cache miss, there is no need to run preprocessor, instead, just fall back directly to running the real compiler, as this will be faster. Is there a way to do it? Thanks, -venkrao ___ ccache mailing list ccache@lists.samba.org https://lists.samba.org/mailman/listinfo/ccache
