This is a revision of an earlier patch, based on comments from Guillem Jover:
http://lists.debian.org/debian-dpkg/2009/10/msg00003.html When running dpkg from a cold cache on a system where /var/lib/dpkg/info/ lies on a harddisk, a lot of time is spent waiting for seeks between (typically) thousands of files. This patch changes the behavior of ensure_allinstfiles_available, so that it accesses the packages in the order of their .list files' physical locations on the harddisk, greatly reducing drive head movements. The performance improvement is around 330% on my system: reinstalling a simple package takes 8 seconds instead of 27 seconds. I dropped the caches before each run, and did 10 runs with consistent results. The performance is identical to the previous patch using FIBMAP. --- configure.ac | 2 +- src/filesdb.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++++++++++--- src/main.h | 1 + 3 files changed, 75 insertions(+), 5 deletions(-) diff --git a/configure.ac b/configure.ac index 2272eb0..54cdb6f 100644 --- a/configure.ac +++ b/configure.ac @@ -79,7 +79,7 @@ fi # Checks for header files. AC_HEADER_STDC AC_CHECK_HEADERS([stddef.h error.h locale.h libintl.h kvm.h \ - sys/cdefs.h sys/syscall.h]) + sys/cdefs.h sys/syscall.h linux/fiemap.h]) DPKG_CHECK_DEFINE(TIOCNOTTY, [sys/ioctl.h]) # Checks for typedefs, structures, and compiler characteristics. diff --git a/src/filesdb.c b/src/filesdb.c index 0cc0791..a2eda65 100644 --- a/src/filesdb.c +++ b/src/filesdb.c @@ -26,6 +26,12 @@ #include <sys/types.h> #include <sys/stat.h> +#if HAVE_LINUX_FIEMAP_H +#include <linux/fiemap.h> +#include <linux/fs.h> +#include <sys/ioctl.h> +#endif + #include <assert.h> #include <errno.h> #include <string.h> @@ -40,6 +46,7 @@ #include <dpkg/dpkg-db.h> #include <dpkg/path.h> #include <dpkg/buffer.h> +#include <dpkg/pkg-array.h> #include <dpkg/progress.h> #include "filesdb.h" @@ -60,6 +67,7 @@ ensure_package_clientdata(struct pkginfo *pkg) pkg->clientdata->fileslistvalid = 0; pkg->clientdata->files = NULL; pkg->clientdata->trigprocdeferred = NULL; + pkg->clientdata->listfile_phys_offset = 0; } void note_must_reread_files_inpackage(struct pkginfo *pkg) { @@ -254,10 +262,29 @@ ensure_packagefiles_available(struct pkginfo *pkg) pkg->clientdata->fileslistvalid= 1; } +#if HAVE_LINUX_FIEMAP_H +int +pkg_sorter_by_listfile_phys_offset(const void *a, const void *b) { + struct pkginfo *const *lhs = a; + struct pkginfo *const *rhs = b; + + /* We can't simply subtract, because the difference may be greater than INT_MAX. + */ + if((*lhs)->clientdata->listfile_phys_offset < (*rhs)->clientdata->listfile_phys_offset) + return -1; + else + return 1; +} +#endif + void ensure_allinstfiles_available(void) { - struct pkgiterator *it; struct pkginfo *pkg; struct progress progress; + struct pkg_array array; + int i; +#if HAVE_LINUX_FIEMAP_H + int blocksize; +#endif if (allpackagesdone) return; if (saidread<2) { @@ -267,14 +294,56 @@ void ensure_allinstfiles_available(void) { progress_init(&progress, _("(Reading database ... "), max); } - it= iterpkgstart(); - while ((pkg = iterpkgnext(it)) != NULL) { + pkg_array_init_from_db(&array); + + /* Sort packages by the physical location of their list files, so that + * scanning them later will minimize disk drive head movements. + */ +#if HAVE_LINUX_FIEMAP_H + for (i = 0; i < array.n_pkgs; i++) { + pkg = array.pkgs[i]; + if(!pkg->clientdata->listfile_phys_offset + && pkg->status != stat_notinstalled) { + struct { + struct fiemap fiemap; + struct fiemap_extent extent; + } fm; + const char *listfile; + int fd; + + pkg->clientdata->listfile_phys_offset = -1; + + listfile= pkgadminfile(pkg, LISTFILE); + + if(-1 == (fd= open(listfile, O_RDONLY))) + continue; + + if(!blocksize && -1 == ioctl(fd, FIGETBSZ, &blocksize)) + break; + + memset(&fm, 0, sizeof(fm)); + fm.fiemap.fm_start = 0; + fm.fiemap.fm_length = blocksize; + fm.fiemap.fm_flags = 0; + fm.fiemap.fm_extent_count = 1; + + if(-1 != ioctl(fd, FS_IOC_FIEMAP, (unsigned long) &fm)) + pkg->clientdata->listfile_phys_offset = fm.fiemap.fm_extents[0].fe_physical; + + close(fd); + } + } + pkg_array_sort(&array, pkg_sorter_by_listfile_phys_offset); +#endif + + for (i = 0; i < array.n_pkgs; i++) { + pkg = array.pkgs[i]; ensure_packagefiles_available(pkg); if (saidread == 1) progress_step(&progress); } - iterpkgend(it); + allpackagesdone= 1; if (saidread==1) { diff --git a/src/main.h b/src/main.h index cbcc2df..eefabff 100644 --- a/src/main.h +++ b/src/main.h @@ -46,6 +46,7 @@ struct perpackagestate { /* Non-NULL iff in trigproc.c:deferred. */ struct pkg_list *trigprocdeferred; + off_t listfile_phys_offset; }; enum action { -- 1.6.4.3 -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected]
