https://sourceware.org/bugzilla/show_bug.cgi?id=27673
Bug ID: 27673
Summary: [debuginfod] Handle source requests for same buildid
more efficiently
Product: elfutils
Version: unspecified
Status: NEW
Severity: enhancement
Priority: P2
Component: debuginfod
Assignee: unassigned at sourceware dot org
Reporter: vries at gcc dot gnu.org
CC: elfutils-devel at sourceware dot org
Target Milestone: ---
Consider the following debuginfod usage session from gdb (reported in gdb
PR27667):
...
$ time gdb -batch -q ./mi-sym-info -ex start -ex "interpreter-exec mi
111-symbol-info-functions" > OUTPUT
TRYING DEBUGINFO FOR: /data/gdb_versions/devel/system-supplied DSO at
0x7ffff7fca000
BUILDID: e77a560007595d823e2c5a34697c0b0ae1ffc767
TOOK: 0.000084 seconds
RESULT fd: 16
TRYING SOURCE:
/home/abuild/rpmbuild/BUILD/gcc-10.2.1+git1331/obj-x86_64-suse-linux/x86_64-suse-linux/libgcc/../../../libgcc/config/i386/sfp-exceptions.c
BUILDID: d34928e1b5c7bde5e269e47349ade7369a3efa83
TOOK: 0.601374 seconds
RESULT fd: -2
TRYING SOURCE:
/home/abuild/rpmbuild/BUILD/gcc-10.2.1+git1331/obj-x86_64-suse-linux/x86_64-suse-linux/libgcc/../../../libgcc/libgcc2.c
BUILDID: d34928e1b5c7bde5e269e47349ade7369a3efa83
TOOK: 0.486450 seconds
RESULT fd: -2
TRYING SOURCE:
/home/abuild/rpmbuild/BUILD/gcc-10.2.1+git1331/obj-x86_64-suse-linux/x86_64-suse-linux/libgcc/../../../libgcc/libgcc2.c
BUILDID: d34928e1b5c7bde5e269e47349ade7369a3efa83
TOOK: 0.493712 seconds
RESULT fd: -2
TRYING SOURCE:
/home/abuild/rpmbuild/BUILD/gcc-10.2.1+git1331/obj-x86_64-suse-linux/x86_64-suse-linux/libgcc/../../../libgcc/libgcc2.c
BUILDID: d34928e1b5c7bde5e269e47349ade7369a3efa83
TOOK: 0.487850 seconds
RESULT fd: -2
TRYING SOURCE:
/home/abuild/rpmbuild/BUILD/gcc-10.2.1+git1331/obj-x86_64-suse-linux/x86_64-suse-linux/libgcc/../../../libgcc/libgcc2.c
BUILDID: d34928e1b5c7bde5e269e47349ade7369a3efa83
TOOK: 0.488300 seconds
RESULT fd: -2
TRYING SOURCE:
/home/abuild/rpmbuild/BUILD/gcc-10.2.1+git1331/obj-x86_64-suse-linux/x86_64-suse-linux/libgcc/../../../libgcc/libgcc2.c
BUILDID: 7076274fc469c32fa8f4201f467447da3ad2b6be
TOOK: 0.493761 seconds
RESULT fd: -2
TRYING SOURCE:
/home/abuild/rpmbuild/BUILD/gcc-10.2.1+git1331/obj-x86_64-suse-linux/x86_64-suse-linux/libgcc/../../../libgcc/soft-fp/addtf3.c
BUILDID: d34928e1b5c7bde5e269e47349ade7369a3efa83
TOOK: 0.486202 seconds
RESULT fd: -2
TRYING SOURCE:
/home/abuild/rpmbuild/BUILD/gcc-10.2.1+git1331/obj-x86_64-suse-linux/x86_64-suse-linux/libgcc/../../../libgcc/soft-fp/divtf3.c
BUILDID: d34928e1b5c7bde5e269e47349ade7369a3efa83
TOOK: 0.485941 seconds
RESULT fd: -2
TRYING SOURCE:
/home/abuild/rpmbuild/BUILD/gcc-10.2.1+git1331/obj-x86_64-suse-linux/x86_64-suse-linux/libgcc/../../../libgcc/soft-fp/eqtf2.c
BUILDID: d34928e1b5c7bde5e269e47349ade7369a3efa83
TOOK: 0.477989 seconds
RESULT fd: -2
TRYING SOURCE:
/home/abuild/rpmbuild/BUILD/gcc-10.2.1+git1331/obj-x86_64-suse-linux/x86_64-suse-linux/libgcc/../../../libgcc/soft-fp/extenddftf2.c
BUILDID: d34928e1b5c7bde5e269e47349ade7369a3efa83
TOOK: 0.487699 seconds
RESULT fd: -2
TRYING SOURCE:
/home/abuild/rpmbuild/BUILD/gcc-10.2.1+git1331/obj-x86_64-suse-linux/x86_64-suse-linux/libgcc/../../../libgcc/soft-fp/fixtfdi.c
BUILDID: d34928e1b5c7bde5e269e47349ade7369a3efa83
TOOK: 0.488412 seconds
RESULT fd: -2
TRYING SOURCE:
/home/abuild/rpmbuild/BUILD/gcc-10.2.1+git1331/obj-x86_64-suse-linux/x86_64-suse-linux/libgcc/../../../libgcc/soft-fp/fixtfsi.c
BUILDID: d34928e1b5c7bde5e269e47349ade7369a3efa83
TOOK: 0.496897 seconds
RESULT fd: -2
TRYING SOURCE:
/home/abuild/rpmbuild/BUILD/gcc-10.2.1+git1331/obj-x86_64-suse-linux/x86_64-suse-linux/libgcc/../../../libgcc/soft-fp/floatditf.c
BUILDID: d34928e1b5c7bde5e269e47349ade7369a3efa83
TOOK: 0.492576 seconds
RESULT fd: -2
TRYING SOURCE:
/home/abuild/rpmbuild/BUILD/gcc-10.2.1+git1331/obj-x86_64-suse-linux/x86_64-suse-linux/libgcc/../../../libgcc/soft-fp/floatsitf.c
BUILDID: d34928e1b5c7bde5e269e47349ade7369a3efa83
TOOK: 0.477747 seconds
RESULT fd: -2
TRYING SOURCE:
/home/abuild/rpmbuild/BUILD/gcc-10.2.1+git1331/obj-x86_64-suse-linux/x86_64-suse-linux/libgcc/../../../libgcc/soft-fp/floatunsitf.c
BUILDID: d34928e1b5c7bde5e269e47349ade7369a3efa83
TOOK: 0.480452 seconds
RESULT fd: -2
TRYING SOURCE:
/home/abuild/rpmbuild/BUILD/gcc-10.2.1+git1331/obj-x86_64-suse-linux/x86_64-suse-linux/libgcc/../../../libgcc/soft-fp/getf2.c
BUILDID: d34928e1b5c7bde5e269e47349ade7369a3efa83
TOOK: 0.487295 seconds
RESULT fd: -2
TRYING SOURCE:
/home/abuild/rpmbuild/BUILD/gcc-10.2.1+git1331/obj-x86_64-suse-linux/x86_64-suse-linux/libgcc/../../../libgcc/soft-fp/letf2.c
BUILDID: d34928e1b5c7bde5e269e47349ade7369a3efa83
TOOK: 0.479365 seconds
RESULT fd: -2
TRYING SOURCE:
/home/abuild/rpmbuild/BUILD/gcc-10.2.1+git1331/obj-x86_64-suse-linux/x86_64-suse-linux/libgcc/../../../libgcc/soft-fp/multf3.c
BUILDID: d34928e1b5c7bde5e269e47349ade7369a3efa83
TOOK: 0.486071 seconds
RESULT fd: -2
TRYING SOURCE:
/home/abuild/rpmbuild/BUILD/gcc-10.2.1+git1331/obj-x86_64-suse-linux/x86_64-suse-linux/libgcc/../../../libgcc/soft-fp/subtf3.c
BUILDID: d34928e1b5c7bde5e269e47349ade7369a3efa83
TOOK: 0.478588 seconds
RESULT fd: -2
TRYING SOURCE:
/home/abuild/rpmbuild/BUILD/gcc-10.2.1+git1331/obj-x86_64-suse-linux/x86_64-suse-linux/libgcc/../../../libgcc/soft-fp/trunctfdf2.c
BUILDID: d34928e1b5c7bde5e269e47349ade7369a3efa83
TOOK: 0.479030 seconds
RESULT fd: -2
TRYING SOURCE:
/home/abuild/rpmbuild/BUILD/gcc-10.2.1+git1331/obj-x86_64-suse-linux/x86_64-suse-linux/libgcc/../../../libgcc/soft-fp/trunctfsf2.c
BUILDID: d34928e1b5c7bde5e269e47349ade7369a3efa83
TOOK: 0.485941 seconds
RESULT fd: -2
TRYING SOURCE:
/home/abuild/rpmbuild/BUILD/gcc-10.2.1+git1331/obj-x86_64-suse-linux/x86_64-suse-linux/libgcc/../../../libgcc/soft-fp/trunctfxf2.c
BUILDID: d34928e1b5c7bde5e269e47349ade7369a3efa83
TOOK: 0.493175 seconds
RESULT fd: -2
TRYING SOURCE:
/home/abuild/rpmbuild/BUILD/gcc-10.2.1+git1331/obj-x86_64-suse-linux/x86_64-suse-linux/libgcc/../../../libgcc/soft-fp/unordtf2.c
BUILDID: d34928e1b5c7bde5e269e47349ade7369a3efa83
TOOK: 0.706890 seconds
RESULT fd: -2
TRYING SOURCE:
/usr/src/debug/kernel-default-5.11.6-1.4.x86_64/linux-5.11/linux-obj/../arch/x86/entry/vdso/../../../../lib/vdso/gettimeofday.c
BUILDID: e77a560007595d823e2c5a34697c0b0ae1ffc767
TOOK: 0.000152 seconds
RESULT fd: 17
TRYING SOURCE:
/usr/src/debug/kernel-default-5.11.6-1.4.x86_64/linux-5.11/linux-obj/../arch/x86/entry/vdso/vclock_gettime.c
BUILDID: e77a560007595d823e2c5a34697c0b0ae1ffc767
TOOK: 0.000094 seconds
RESULT fd: 17
TRYING SOURCE:
/usr/src/debug/kernel-default-5.11.6-1.4.x86_64/linux-5.11/linux-obj/../arch/x86/entry/vdso/vgetcpu.c
BUILDID: e77a560007595d823e2c5a34697c0b0ae1ffc767
TOOK: 0.000117 seconds
RESULT fd: 17
TRYING SOURCE:
/usr/src/debug/kernel-default-5.11.6-1.4.x86_64/linux-5.11/linux-obj/../arch/x86/include/asm/vdso/gettimeofday.h
BUILDID: e77a560007595d823e2c5a34697c0b0ae1ffc767
TOOK: 0.000061 seconds
RESULT fd: 17
TRYING SOURCE:
/usr/src/debug/glibc-2.33-4.1.x86_64/io/../sysdeps/unix/sysv/linux/wordsize-64/../fstatvfs.c
BUILDID: 7076274fc469c32fa8f4201f467447da3ad2b6be
TOOK: 0.000068 seconds
RESULT fd: 17
TRYING SOURCE:
/usr/src/debug/glibc-2.33-4.1.x86_64/io/../sysdeps/unix/sysv/linux/wordsize-64/../statvfs.c
BUILDID: 7076274fc469c32fa8f4201f467447da3ad2b6be
TOOK: 0.000054 seconds
RESULT fd: 17
TRYING SOURCE: /home/abuild/rpmbuild/BUILD/glibc-2.33/csu/elf-init.c
BUILDID: 00ef641a70731291619bdc1ae4badda60c853386
TOOK: 0.492776 seconds
RESULT fd: -2
real 0m17.807s
user 0m6.203s
sys 0m0.137s
...
If the results are found (fd >= 0), they are quick because they're in the
cache.
There's a PR open about caching negative results, PR25628. That would help, at
least the second time.
But there's another observation to be made: there's a number of files for which
-2 fd is returned with the same buildid. If the server would reply to an
ENOENT source request with a list of files contained in the buildid, then the
client would have the information to answer that request, as well as subsequent
requests using the same buildid. AFAIU, this ties in somewhat with PR27277.
Taking the idea further, a more bandwith-hungry variant would be to answer any
source request with the source archive, after which any source query for that
buildid can be dealt with by the client.
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