| Message ID | 20180703065810.14917-3-mikey@neuling.org |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [1/6] htm: Fix compiling on ARM | expand |
On Tue, 2018-07-03 at 16:58 +1000, Michael Neuling wrote: > Gives 10% speedup for no more complexity. How about copy_file_range()? > > Signed-off-by: Michael Neuling <mikey@neuling.org> > --- > libpdbg/htm.c | 26 ++++++++++++-------------- > 1 file changed, 12 insertions(+), 14 deletions(-) > > diff --git a/libpdbg/htm.c b/libpdbg/htm.c > index fa15f5f5d3..a494493935 100644 > --- a/libpdbg/htm.c > +++ b/libpdbg/htm.c > @@ -952,41 +952,39 @@ static int do_htm_status(struct htm *htm) > return 1; > } > > -#define COPY_BUF_SIZE getpagesize() > static int copy_file(int output, int input, uint64_t size) > { > - char *buf; > size_t r; > + int pipefd[2]; > + int rc = -1; > > - buf = malloc(COPY_BUF_SIZE); > - if (!buf) { > - PR_ERROR("Can't malloc buffer\n"); > - return -1; > + if (pipe(pipefd)) { > + perror("pipe"); > + exit(1); > } > > while (size) { > - r = read(input, buf, MIN(COPY_BUF_SIZE, size)); > + r = splice(input, 0, pipefd[1], 0, size, 0); > if (r == -1) { > PR_ERROR("Failed to read\n"); > goto out; > } > if (r == 0) { > - PR_ERROR("EOF\n"); > + PR_ERROR("Unexpect EOF\n"); > goto out; > } > > - if (write(output, buf, r) != r) { > + if (splice(pipefd[0], 0, output, 0, r, 0) != r) { > PR_ERROR("Short write!\n"); > goto out; > } > size -= r; > } > - > - return 0; > - > + rc = 0; > out: > - free(buf); > - return -1; > + close(pipefd[1]); > + close(pipefd[0]); > + return rc; > > } > > -- > 2.17.1 > Amitay.
On Wed, 2018-07-04 at 14:18 +1000, Amitay Isaacs wrote: > On Tue, 2018-07-03 at 16:58 +1000, Michael Neuling wrote: > > Gives 10% speedup for no more complexity. > > How about copy_file_range()? Nice but it doesn't work since the FDs are on different filesystems (debugfs vs real disk) The man page confirms this: ERRORS: .... EXDEV The files referred to by file_in and file_out are not on the same mounted filesystem. Mikey
Out of interest I hacked up a test using sendfile. Results on my laptop were about the same as using the splice method from this patch. Arguably using sendfile is cleaner as you don't need the pipe but this patch is perfectly readable so I've merged it for now. Thanks Mikey. - Alistair On Thursday, 5 July 2018 5:48:12 PM AEST Michael Neuling wrote: > On Wed, 2018-07-04 at 14:18 +1000, Amitay Isaacs wrote: > > On Tue, 2018-07-03 at 16:58 +1000, Michael Neuling wrote: > > > Gives 10% speedup for no more complexity. > > > > How about copy_file_range()? > > Nice but it doesn't work since the FDs are on different filesystems (debugfs vs > real disk) > > The man page confirms this: > > ERRORS: > .... > EXDEV The files referred to by file_in and file_out are not on the > > same mounted filesystem. > > Mikey >
On Thu, 2018-07-12 at 13:52 +1000, Alistair Popple wrote: > Out of interest I hacked up a test using sendfile. Results on my laptop were > about the same as using the splice method from this patch. Arguably using > sendfile is cleaner as you don't need the pipe but this patch is perfectly > readable so I've merged it for now. Thanks Mikey. Thanks. I think in the end we get limited by reading the trace from the CI mapped memory. So there is only so far we can optimise it. Mikey
diff --git a/libpdbg/htm.c b/libpdbg/htm.c index fa15f5f5d3..a494493935 100644 --- a/libpdbg/htm.c +++ b/libpdbg/htm.c @@ -952,41 +952,39 @@ static int do_htm_status(struct htm *htm) return 1; } -#define COPY_BUF_SIZE getpagesize() static int copy_file(int output, int input, uint64_t size) { - char *buf; size_t r; + int pipefd[2]; + int rc = -1; - buf = malloc(COPY_BUF_SIZE); - if (!buf) { - PR_ERROR("Can't malloc buffer\n"); - return -1; + if (pipe(pipefd)) { + perror("pipe"); + exit(1); } while (size) { - r = read(input, buf, MIN(COPY_BUF_SIZE, size)); + r = splice(input, 0, pipefd[1], 0, size, 0); if (r == -1) { PR_ERROR("Failed to read\n"); goto out; } if (r == 0) { - PR_ERROR("EOF\n"); + PR_ERROR("Unexpect EOF\n"); goto out; } - if (write(output, buf, r) != r) { + if (splice(pipefd[0], 0, output, 0, r, 0) != r) { PR_ERROR("Short write!\n"); goto out; } size -= r; } - - return 0; - + rc = 0; out: - free(buf); - return -1; + close(pipefd[1]); + close(pipefd[0]); + return rc; }
Gives 10% speedup for no more complexity. Signed-off-by: Michael Neuling <mikey@neuling.org> --- libpdbg/htm.c | 26 ++++++++++++-------------- 1 file changed, 12 insertions(+), 14 deletions(-)