database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2026-10-23 18:49:29 +03:00
Code Activity

pread_write(): Copy 1MiB at a time, and invoke Linux readahead(2)

Browse Source
This commit is contained in:
Marko Mäkelä
2026-10-19 11:49:59 +03:00
parent 5d0d773acd
commit 67de2c5065
1 changed files with 10 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
sql/sql_backup.cc
View File

@@ -90,7 +90,8 @@ template<bool stream>
static ssize_t pread_write(backup::handle in_fd, backup_fd out_fd,
uint64_t o, uint64_t end) noexcept
{
#ifdef POSIX_FADV_SEQUENTIAL
#ifdef __linux__
#elif defined POSIX_FADV_SEQUENTIAL
std::ignore= posix_fadvise(in_fd, o, end - o, POSIX_FADV_SEQUENTIAL);
#endif
assert(end >= o);
@@ -98,7 +99,7 @@ static ssize_t pread_write(backup::handle in_fd, backup_fd out_fd,
#if SIZEOF_SIZE_T < 8
size_t size{65536};
#else
constexpr size_t max_size{16 << 20};
constexpr size_t max_size{1 << 20};
/* An integer multiple of 4096 bytes, up to max_size */
size_t size{count >= max_size ? max_size : (size_t(count) + 4095) & ~4095};
#endif
@@ -106,15 +107,20 @@ static ssize_t pread_write(backup::handle in_fd, backup_fd out_fd,
if (!b)
return -1;
ssize_t ret;
for (;; o+= ret)
for (;;)
{
if (count < size)
size= count;
ret= pread(in_fd, b, ssize_t(size), o);
count-= uint64_t(ret);
const uint64_t n{o + ret};
if (ret > 0)
{
#ifdef POSIX_FADV_DONTNEED
std::ignore= posix_fadvise(in_fd, o, ret, POSIX_FADV_DONTNEED);
#endif
#ifdef __linux__
readahead(in_fd, n, count);
#endif
if (!stream)
ret= pwrite(out_fd, b, size_t(ret), o);
@@ -126,7 +132,6 @@ static ssize_t pread_write(backup::handle in_fd, backup_fd out_fd,
}
if (ret < 0)
break;
count-= uint64_t(ret);
if (!count)
{
ret= 0;
@@ -137,6 +142,7 @@ static ssize_t pread_write(backup::handle in_fd, backup_fd out_fd,
ret= -1;
break;
}
o= n;
}
aligned_free(b);
return ret;