Hello Dave, These two patches are used to improve the performance of "kmem -s [address]". Current code need to search all kmem_caches twice. It is a waste of time. With my patch, the address is sent to "dump_kmem_cache" function to make the second search be restricted to the kmem_cache found in the first search. It means the second search is neglected. I have implemented the improvement for three types of kmem_cache. The search for "slub" does not waste that much time as its peers, so I did not modify the code related to "slub". Additionally, I only get the environment to test my first patch, so the second patch has not been tested. Here is the statistic of my test on RHEL6.2 x86_64, the vmcore used for testing has about 150000 kmem_caches commands in file: 1. only 'quit' origin code : about 36s with patch : about 36s 2. 1 time of searching the 100000th kmem_cache origin code : about 59s with patch : about 39s 3. 100 times of searching the 100000th kmem_cache origin code : about 38min30s with patch : about 5min

p.s. If I create a kmem_cache called "list", a little confusion may happen when using "kmem -s list". I am wondering is it necessary to introduce an another option replacing list to avoid such collision.

----- Original Message ----- > > That all being said, your patch does have merit -- presuming that > the meminfo.cache field *never* gets set elsewhere prior to entering > the dump_kmem_cache_xxx functions. I haven't taken the time to > verify that -- did you absolutely verify that? It looks OK to use "if (si->cache)" in those 3 locations -- but it would be safer to create/set a unique meminfo->flags bit for this feature.

Dave -- Crash-utility mailing list Crash-utility(a)redhat.com https://www.redhat.com/mailman/listinfo/crash-utility

But in other circumstances where there may be ambiguity, I've put in the option of putting a "\" in front of the name, i.e., you could do something like: crash> kmem -s list ffff880079e44a00 nfs_read_data ffff880079e44700 nfs_inode_cache ffff880079e44d00 fscache_cookie_jar ... crash> kmem -s \list CACHE NAME OBJSIZE ALLOCATED TOTAL SLABS SSIZE ffff88007b895400 list 240 0 0 0 4k crash> That would be simple enough fix in cmd_kmem() if you re-work this part: if (sflag == 1) { if (STREQ(meminfo.reqname, "list")) kmem_cache_list(); else if (vt->flags& KMEM_CACHE_UNAVAIL) error(FATAL, "kmem cache slab subsystem not available\n"); else vt->dump_kmem_cache(&meminfo); }

At 2012-2-3 15:19, qiaonuohan wrote: > At 2012-2-3 1:24, Dave Anderson wrote: >> But in other circumstances where there may be ambiguity, I've put >> in the option of putting a "\" in front of the name, i.e., you >> could do something like: >> >> crash> kmem -s list >> ffff880079e44a00 nfs_read_data >> ffff880079e44700 nfs_inode_cache >> ffff880079e44d00 fscache_cookie_jar >> ... >> >> crash> kmem -s \list >> CACHE NAME OBJSIZE ALLOCATED TOTAL SLABS SSIZE >> ffff88007b895400 list 240 0 0 0 4k >> crash> >> >> That would be simple enough fix in cmd_kmem() if you re-work this >> part: >> >> if (sflag == 1) { >> if (STREQ(meminfo.reqname, "list")) >> kmem_cache_list(); >> else if (vt->flags& KMEM_CACHE_UNAVAIL) >> error(FATAL, >> "kmem cache slab subsystem not available\n"); >> else >> vt->dump_kmem_cache(&meminfo); >> } > Hello Dave, > > Thanks for your advice! But after some investigation, "\list" may also > involve ambiguity. I created a kmem_cache called "\list", the original > code can display the following information after executing "kmem -s > \list". > > crash> kmem -s \list > CACHE NAME OBJSIZE ALLOCATED TOTAL SLABS SSIZE > ffff880874b30c40 \list 8 0 0 0 4k > crash> > > Need to use "\\list" to refer the kmem_cache called "\list" if code is > changed? Please! I find it is better to remain the original code. Could > you give me some tips? > I figured out a style of the command which seems somewhat suitable. If the "name" of "kmem -s <name>" starts with a "\", neglect it and search the slab by the remaining part. Some examples are listed below: command argument slab name -------------------------------------------- \list list \\list \list \\\list \\list kvm_vcpu kvm_vcpu \kvm_vcpu kvm_vcpu \\kvm_vcpu \kvm_vcpu Is this acceptable? If so, I will do the fix like this.