On Thu, Dec 19, 2024 at 9:51 AM Darrick J. Wong <djwong@xxxxxxxxxx> wrote:
>
> 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
> > +
> > 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 point, the user could potentially request an alignment that's a
multiple. I'll account for this in v2.
>
> > + 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?
good_buf is used too as the source buffer for the write in dowrite().
Thanks,
Joanne
>
> --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
> >
> >
