Messages in this thread Patch in this message | | | Date | Sat, 13 May 2006 11:19:46 -0700 | From | Valerie Henson <> | Subject | Re: [patch 00/14] remap_file_pages protection support |
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On Sun, May 14, 2006 at 12:13:21AM +1000, Nick Piggin wrote: > > OK, I got interested again, but can't get Val's ebizzy to give me > a find_vma constrained workload yet (though the numbers back up > my assertion that the vma cache is crap for threaded apps).
Hey Nick,
Glad to see you're using it! There are (at least) two ways to do what you want:
1. Increase the number of threads - this gives you two vma's per thread, one for stack, one for guard page:
$ ./ebizzy -t 100
2. Apply the patch at the end of this email and use -p "prevent coalescing", -m "always mmap" and appropriate number of chunks, size, and records to search - this works for me:
$ ./ebizzy -p -m -n 10000 -s 4096 -r 100000
The original program mmapped everything with the same permissions and no alignment restrictions, so all the mmaps were coalesced into one. This version alternates PROT_WRITE permissions on the mmap'd areas after they are written, so you get lots of vma's:
val@goober:~/ebizzy$ ./ebizzy -p -m -n 10000 -s 4096 -r 100000
[2]+ Stopped ./ebizzy -p -m -n 10000 -s 4096 -r 100000 val@goober:~/ebizzy$ wc -l /proc/`pgrep ebizzy`/maps 10019 /proc/10917/maps
I haven't profiled to see if this brings find_vma to the top, though.
(The patch also moves around some other stuff so that options are in alphabetical order; apparently I thought 's' came after 'r' and before 'R'...)
-VAL
--- ebizzy.c.old 2006-05-13 10:18:58.000000000 -0700 +++ ebizzy.c 2006-05-13 11:01:42.000000000 -0700 @@ -52,9 +52,10 @@ static unsigned int always_mmap; static unsigned int never_mmap; static unsigned int chunks; +static unsigned int prevent_coalescing; static unsigned int records; -static unsigned int chunk_size; static unsigned int random_size; +static unsigned int chunk_size; static unsigned int threads; static unsigned int verbose; static unsigned int linear; @@ -76,9 +77,10 @@ "-m\t\t Always use mmap instead of malloc\n" "-M\t\t Never use mmap\n" "-n <num>\t Number of memory chunks to allocate\n" + "-p \t\t Prevent mmap coalescing\n" "-r <num>\t Total number of records to search for\n" - "-s <size>\t Size of memory chunks, in bytes\n" "-R\t\t Randomize size of memory to copy and search\n" + "-s <size>\t Size of memory chunks, in bytes\n" "-t <num>\t Number of threads\n" "-v[v[v]]\t Be verbose (more v's for more verbose)\n" "-z\t\t Linear search instead of binary search\n", @@ -98,7 +100,7 @@ cmd = argv[0]; opterr = 1; - while ((c = getopt(argc, argv, "mMn:r:s:Rt:vz")) != -1) { + while ((c = getopt(argc, argv, "mMn:pr:Rs:t:vz")) != -1) { switch (c) { case 'm': always_mmap = 1; @@ -111,19 +113,22 @@ if (chunks == 0) usage(); break; + case 'p': + prevent_coalescing = 1; + break; case 'r': records = atoi(optarg); if (records == 0) usage(); break; + case 'R': + random_size = 1; + break; case 's': chunk_size = atoi(optarg); if (chunk_size == 0) usage(); break; - case 'R': - random_size = 1; - break; case 't': threads = atoi(optarg); if (threads == 0) @@ -141,7 +146,7 @@ } if (verbose) - printf("ebizzy 0.1, Copyright 2006 Intel Corporation\n" + printf("ebizzy 0.2, Copyright 2006 Intel Corporation\n" "Written by Val Henson <val_henson@linux.intel.com\n"); /* @@ -173,10 +178,11 @@ printf("always_mmap %u\n", always_mmap); printf("never_mmap %u\n", never_mmap); printf("chunks %u\n", chunks); + printf("prevent coalescing %u\n", prevent_coalescing); printf("records %u\n", records); printf("records per thread %u\n", records_per_thread); - printf("chunk_size %u\n", chunk_size); printf("random_size %u\n", random_size); + printf("chunk_size %u\n", chunk_size); printf("threads %u\n", threads); printf("verbose %u\n", verbose); printf("linear %u\n", linear); @@ -251,9 +257,13 @@ { int i, j; - for (i = 0; i < chunks; i++) + for (i = 0; i < chunks; i++) { for(j = 0; j < chunk_size / record_size; j++) mem[i][j] = (record_t) j; + /* Prevent coalescing by alternating permissions */ + if (prevent_coalescing && (i % 2) == 0) + mprotect(mem[i], chunk_size, PROT_READ); + } if (verbose) printf("Wrote memory\n"); } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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