Bug 662011
| Summary: | ls -l command make two getxattr() when both call files with ENODATA | ||
|---|---|---|---|
| Product: | [Fedora] Fedora | Reporter: | Lakshmipathi <lakshmipathi.g> |
| Component: | acl | Assignee: | Steve Dickson <steved> |
| Status: | CLOSED NOTABUG | QA Contact: | Fedora Extras Quality Assurance <extras-qa> |
| Severity: | low | Docs Contact: | |
| Priority: | low | ||
| Version: | rawhide | CC: | aquini, kdudka, ovasik, steved, twaugh |
| Target Milestone: | --- | Keywords: | Reopened |
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2010-12-10 12:13:10 UTC | Type: | --- |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
The first ENODATA does not imply the second one. Those need to be checked separately. Try the following example:
$ mkdir d
$ setfacl -d -m user:root:rwx d
$ strace -e trace=getxattr ls -ld d
getxattr("d", "system.posix_acl_access", 0x0, 0) = -1 ENODATA (No data available)
getxattr("d", "system.posix_acl_default", 0x0, 0) = 44
In your example you have created a directory ,what about providing check to make sure if its a file the ignore the second call. I have ran tests with 100000 files and found that getxattr alone takes around 20% of ls time. If second call is ignored i believe it would increase ls performance by 10%. ================= % time seconds usecs/call calls errors syscall ------ ----------- ----------- --------- --------- ---------------- 45.75 0.047209 390 121 getdents 20.89 0.021563 0 200000 200000 getxattr ================= That is, however, not easily doable. coreutils uses file_has_acl() from gnulib. On Linux it results to call of acl_extended_file() from libacl. The function operates on file name and has no stat info available. In order to skip the second call of getxattr(), it would be necessary to insert additional call of stat(). That is totally pointless, since the second call of getxattr() on the same file has zero cost. It just serves the data from cache. Your statistics says nothing about the proposed change. You need to run it through strace -r and check the delay of even calls of getxattr() only. Alternatively you can force through LD_PRELOAD your own implementation of acl_extended_file() with the stat() inserted and see if there is some measurable performance improvement. 1) F-12 is EOLed ... -> moving to Rawhide 2) these two getxattr calls are not from coreutils, but from libacl (acl_extended_file() function) - and it's parameter is just name of the file -> moving to acl. So making the second getxattr only on directories, it would probably mean to call another stat call - which would mean anothere decrease of the performance (probably as significant as the second getxattr call) - reassigning to acl, and ... Kamil will probably close it again NOTABUG. okay.When i get time ,i'll look into libacl code to see anything is possible to handle this case..thanks for comments. |
Description of problem: ls -l command make two getxattr() $touch a $ strace -e trace="getxattr" ls -l a getxattr("a", "system.posix_acl_access", 0x0, 0) = -1 ENODATA (No data available) getxattr("a", "system.posix_acl_default", 0x0, 0) = -1 ENODATA (No data available) Version-Release number of selected component (if applicable): coreutils-7.6-11.fc12.x86_64 How reproducible: $touch filename.txt $ strace -e trace="getxattr" ls -l filename.txt Actual results: performs two calls getxattr("a", "system.posix_acl_access", 0x0, 0) = -1 ENODATA (No data available) getxattr("a", "system.posix_acl_default", 0x0, 0) = -1 ENODATA (No data available) Expected results: I think it would be better, if call first fails - we need ignore the second getxattr() call. getxattr("a", "system.posix_acl_access", 0x0, 0) = -1 ENODATA (No data available) This would increase the performance on directories which has huge no.of files. Additional info: