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Linux: Use copy_file_range for defrag of the disk cache which should give even better performance on filesystems that support it

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This commit is contained in:
Kovid Goyal 2021-11-24 19:42:00 +05:30
parent bd21b79959
commit 617316e8d9
No known key found for this signature in database
GPG Key ID: 06BC317B515ACE7C
2 changed files with 61 additions and 27 deletions
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85
kitty/fast-file-copy.c
View File

@ -5,39 +5,20 @@
* Distributed under terms of the GPL3 license.
*/
#if __linux__
#define _GNU_SOURCE 1
#endif
#include "fast-file-copy.h"
#if __linux__
#define HAS_SENDFILE
#include <sys/sendfile.h>
#include <unistd.h>
#endif
#ifdef HAS_SENDFILE
static bool
copy_with_sendfile(int infd, int outfd, off_t in_pos, size_t len) {
unsigned num_of_consecutive_zero_returns = 128;
while (len) {
off_t r = in_pos;
ssize_t n = sendfile(outfd, infd, &r, len);
if (n < 0) {
if (errno != EAGAIN) return false;
continue;
}
if (n == 0) {
// happens if input file is truncated
if (!--num_of_consecutive_zero_returns) return false;
continue;
};
num_of_consecutive_zero_returns = 128;
in_pos += n; len -= n;
}
return true;
}
#endif
static inline bool
copy_with_buffer(int infd, int outfd, off_t in_pos, size_t len, FastFileCopyBuffer *fcb) {
if (!fcb->buf) {
fcb->sz = 16 * 1024;
fcb->sz = 32 * 1024;
fcb->buf = malloc(fcb->sz);
if (!fcb->buf) return false;
}
@ -69,14 +50,64 @@ copy_with_buffer(int infd, int outfd, off_t in_pos, size_t len, FastFileCopyBuff
}
}
return true;
#undef bufsz
}
#ifdef HAS_SENDFILE
static bool
copy_with_sendfile(int infd, int outfd, off_t in_pos, size_t len, FastFileCopyBuffer *fcb) {
unsigned num_of_consecutive_zero_returns = 128;
while (len) {
off_t r = in_pos;
ssize_t n = sendfile(outfd, infd, &r, len);
if (n < 0) {
if (errno != EAGAIN) return false;
if (errno == ENOSYS || errno == EPERM) return copy_with_buffer(infd, outfd, in_pos, len, fcb);
continue;
}
if (n == 0) {
// happens if input file is truncated
if (!--num_of_consecutive_zero_returns) return false;
continue;
};
num_of_consecutive_zero_returns = 128;
in_pos += n; len -= n;
}
return true;
}
static bool
copy_with_file_range(int infd, int outfd, off_t in_pos, size_t len, FastFileCopyBuffer *fcb) {
#ifdef HAS_COPY_FILE_RANGE
unsigned num_of_consecutive_zero_returns = 128;
while (len) {
off64_t r = in_pos;
ssize_t n = copy_file_range(infd, &r, outfd, NULL, len, 0);
if (n < 0) {
if (errno != EAGAIN) return false;
if (errno == ENOSYS || errno == EPERM) return copy_with_sendfile(infd, outfd, in_pos, len, fcb);
continue;
}
if (n == 0) {
// happens if input file is truncated
if (!--num_of_consecutive_zero_returns) return false;
continue;
};
num_of_consecutive_zero_returns = 128;
in_pos += n; len -= n;
}
return true;
#else
return copy_with_sendfile(infd, outfd, in_pos, len, fcb);
#endif
}
#endif
bool
copy_between_files(int infd, int outfd, off_t in_pos, size_t len, FastFileCopyBuffer *fcb) {
#ifdef HAS_SENDFILE
(void)fcb;
return copy_with_sendfile(infd, outfd, in_pos, len);
return copy_with_file_range(infd, outfd, in_pos, len, fcb);
#else
return copy_with_buffer(infd, outfd, in_pos, len, fcb);
#endif

3
setup.py
View File

@ -326,6 +326,9 @@ def init_env(
cppflags = shlex.split(cppflags_)
for el in extra_logging:
cppflags.append('-DDEBUG_{}'.format(el.upper().replace('-', '_')))
has_copy_file_range = test_compile(cc, src='#define _GNU_SOURCE 1\n#include <unistd.h>\nint main() { copy_file_range(1, NULL, 2, NULL, 0, 0); return 0; }')
if has_copy_file_range:
cppflags.append('-DHAS_COPY_FILE_RANGE')
werror = '' if ignore_compiler_warnings else '-pedantic-errors -Werror'
std = '' if is_openbsd else '-std=c11'
sanitize_flag = ' '.join(sanitize_args)