On Wed, Dec 18, 2024 at 01:01:21PM -0800, Joanne Koong wrote:
> Add support for reads/writes from buffers backed by hugepages.
> This can be enabled through the '-h' flag. This flag should only be used
> on systems where THP capabilities are enabled.
>
> Signed-off-by: Joanne Koong <joannelkoong@xxxxxxxxx>
> ---
> ltp/fsx.c | 100 +++++++++++++++++++++++++++++++++++++++++++++++++-----
> 1 file changed, 92 insertions(+), 8 deletions(-)
>
> diff --git a/ltp/fsx.c b/ltp/fsx.c
> index 41933354..3656fd9f 100644
> --- a/ltp/fsx.c
> +++ b/ltp/fsx.c
> @@ -190,6 +190,7 @@ int o_direct; /* -Z */
> int aio = 0;
> int uring = 0;
> int mark_nr = 0;
> +int hugepages = 0; /* -h flag */
>
> int page_size;
> int page_mask;
> @@ -2471,7 +2472,7 @@ void
> usage(void)
> {
> fprintf(stdout, "usage: %s",
> - "fsx [-dfknqxyzBEFHIJKLORWXZ0]\n\
> + "fsx [-dfhknqxyzBEFHIJKLORWXZ0]\n\
> [-b opnum] [-c Prob] [-g filldata] [-i logdev] [-j logid]\n\
> [-l flen] [-m start:end] [-o oplen] [-p progressinterval]\n\
> [-r readbdy] [-s style] [-t truncbdy] [-w writebdy]\n\
> @@ -2484,6 +2485,7 @@ usage(void)
> -e: pollute post-eof on size changes (default 0)\n\
> -f: flush and invalidate cache after I/O\n\
> -g X: write character X instead of random generated data\n\
> + -h hugepages: use buffers backed by hugepages for reads/writes\n\
> -i logdev: do integrity testing, logdev is the dm log writes device\n\
> -j logid: prefix debug log messsages with this id\n\
> -k: do not truncate existing file and use its size as upper bound on file size\n\
> @@ -2856,6 +2858,56 @@ keep_running(void)
> return numops-- != 0;
> }
>
> +static long
> +get_hugepage_size(void)
> +{
> + const char *str = "Hugepagesize:";
> + long hugepage_size = -1;
> + char buffer[64];
> + FILE *file;
> +
> + file = fopen("/proc/meminfo", "r");
> + if (!file) {
> + prterr("get_hugepage_size: fopen /proc/meminfo");
> + return -1;
> + }
> + while (fgets(buffer, sizeof(buffer), file)) {
> + if (strncmp(buffer, str, strlen(str)) == 0) {
> + sscanf(buffer + strlen(str), "%ld", &hugepage_size);
> + break;
> + }
> + }
> + fclose(file);
> + if (hugepage_size == -1) {
> + prterr("get_hugepage_size: failed to find "
> + "hugepage size in /proc/meminfo\n");
> + return -1;
> + }
> +
> + /* convert from KiB to bytes */
> + return hugepage_size * 1024;
> +}
> +
> +static void *
> +init_hugepages_buf(unsigned len, long hugepage_size)
> +{
> + void *buf;
> + long buf_size = roundup(len, hugepage_size);
> +
> + if (posix_memalign(&buf, hugepage_size, buf_size)) {
> + prterr("posix_memalign for buf");
> + return NULL;
> + }
> + memset(buf, '\0', len);
> + if (madvise(buf, buf_size, MADV_COLLAPSE)) {
> + prterr("madvise collapse for buf");
> + free(buf);
> + return NULL;
> + }
> +
> + return buf;
> +}
> +
> static struct option longopts[] = {
> {"replay-ops", required_argument, 0, 256},
> {"record-ops", optional_argument, 0, 255},
> @@ -2883,7 +2935,7 @@ main(int argc, char **argv)
> setvbuf(stdout, (char *)0, _IOLBF, 0); /* line buffered stdout */
>
> while ((ch = getopt_long(argc, argv,
> - "0b:c:de:fg:i:j:kl:m:no:p:qr:s:t:uw:xyABD:EFJKHzCILN:OP:RS:UWXZ",
> + "0b:c:de:fg:hi:j:kl:m:no:p:qr:s:t:uw:xyABD:EFJKHzCILN:OP:RS:UWXZ",
> longopts, NULL)) != EOF)
> switch (ch) {
> case 'b':
> @@ -2916,6 +2968,9 @@ main(int argc, char **argv)
> case 'g':
> filldata = *optarg;
> break;
> + case 'h':
> + hugepages = 1;
> + break;
> case 'i':
> integrity = 1;
> logdev = strdup(optarg);
> @@ -3232,12 +3287,41 @@ main(int argc, char **argv)
> original_buf = (char *) malloc(maxfilelen);
> for (i = 0; i < maxfilelen; i++)
> original_buf[i] = random() % 256;
> - good_buf = (char *) malloc(maxfilelen + writebdy);
> - good_buf = round_ptr_up(good_buf, writebdy, 0);
> - memset(good_buf, '\0', maxfilelen);
> - temp_buf = (char *) malloc(maxoplen + readbdy);
> - temp_buf = round_ptr_up(temp_buf, readbdy, 0);
> - memset(temp_buf, '\0', maxoplen);
> + if (hugepages) {
> + long hugepage_size;
> +
> + hugepage_size = get_hugepage_size();
> + if (hugepage_size == -1) {
> + prterr("get_hugepage_size()");
> + exit(99);
> + }
> +
> + if (writebdy != 1 && writebdy != hugepage_size)
> + prt("ignoring write alignment (since -h is enabled)");
> +
> + if (readbdy != 1 && readbdy != hugepage_size)
> + prt("ignoring read alignment (since -h is enabled)");
What if readbdy is a multiple of the hugepage size?
> + good_buf = init_hugepages_buf(maxfilelen, hugepage_size);
> + if (!good_buf) {
> + prterr("init_hugepages_buf failed for good_buf");
> + exit(100);
> + }
Why is it necessary for the good_buf to be backed by a hugepage?
I thought good_buf was only used to compare file contents?
--D
> +
> + temp_buf = init_hugepages_buf(maxoplen, hugepage_size);
> + if (!temp_buf) {
> + prterr("init_hugepages_buf failed for temp_buf");
> + exit(101);
> + }
> + } else {
> + good_buf = (char *) malloc(maxfilelen + writebdy);
> + good_buf = round_ptr_up(good_buf, writebdy, 0);
> + memset(good_buf, '\0', maxfilelen);
> +
> + temp_buf = (char *) malloc(maxoplen + readbdy);
> + temp_buf = round_ptr_up(temp_buf, readbdy, 0);
> + memset(temp_buf, '\0', maxoplen);
> + }
> if (lite) { /* zero entire existing file */
> ssize_t written;
>
> --
> 2.47.1
>
>
