search for: lock2

On Wed, Apr 01, 2015 at 12:20:30PM -0400, Waiman Long wrote: > After more careful reading, I think the assumption that the presence of an > unused bucket means there is no match is not true. Consider the scenario: > > 1. cpu 0 puts lock1 into hb[0] > 2. cpu 1 puts lock2 into hb[1] > 3. cpu 2 clears hb[0] > 4. cpu 3 looks for lock2 and doesn't find it Hmm, yes. The only way I can see that being true is if we assume entries are never taken out again. The wikipedia page could use some clarification here, this is not clear. > At this point, I am thinki...

On Wed, Apr 01, 2015 at 12:20:30PM -0400, Waiman Long wrote: > After more careful reading, I think the assumption that the presence of an > unused bucket means there is no match is not true. Consider the scenario: > > 1. cpu 0 puts lock1 into hb[0] > 2. cpu 1 puts lock2 into hb[1] > 3. cpu 2 clears hb[0] > 4. cpu 3 looks for lock2 and doesn't find it Hmm, yes. The only way I can see that being true is if we assume entries are never taken out again. The wikipedia page could use some clarification here, this is not clear. > At this point, I am thinki...

I have a data frame (morgan) of hourly river flow, river levels and wind direction and speed thus: Time hour lev.morgan lev.lock2 lev.lock1 flow direction velocity 1 2009-07-06 15:00:00 15 3.266 3.274 3.240 1710.6 180.282 4.352 2 2009-07-06 16:00:00 16 3.268 3.272 3.240 1441.8 192.338 5.496 3 2009-07-06 17:00:00 17 3.268 3.271 3.240 1300.1 202.294 2.695 4 2009...

...* If we hit an unused bucket, there is no match. > + */ > + if (!l) > + goto done; After more careful reading, I think the assumption that the presence of an unused bucket means there is no match is not true. Consider the scenario: 1. cpu 0 puts lock1 into hb[0] 2. cpu 1 puts lock2 into hb[1] 3. cpu 2 clears hb[0] 4. cpu 3 looks for lock2 and doesn't find it I was thinking about putting some USED flag in the buckets, but then we will eventually fill them all up as used. If we put the entries into a hashed linked list, we have to deal with the complicated synchronizatio...

..., Apr 01, 2015 at 12:20:30PM -0400, Waiman Long wrote: > > After more careful reading, I think the assumption that the presence of an > > unused bucket means there is no match is not true. Consider the scenario: > > > > 1. cpu 0 puts lock1 into hb[0] > > 2. cpu 1 puts lock2 into hb[1] > > 3. cpu 2 clears hb[0] > > 4. cpu 3 looks for lock2 and doesn't find it > > Hmm, yes. The only way I can see that being true is if we assume entries > are never taken out again. > > The wikipedia page could use some clarification here, this is not clea...

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 If I use the smbtorture available at ftp://ftp.samba.org/pub/tridge/dbench, I get the following options: tests are: FDPASS LOCK1 LOCK2 LOCK3 UNLINK BROWSE ATTR TRANS2 MAXFID TORTURE RANDOMIPC NBW95 NBWNT default test is ALL But the smbtorture compiled with Gentoo's 3.0.2a gives me tests are: FDPASS LOCK1 LOCK2 LOCK3 LOCK4 LOCK5 LOCK6 LOCK7 UNLINK BROWSE ATTR TRANS2 MAXFID TORTURE RANDOMIPC NEGNOWAIT NBENCH OPLOCK1 OPLOCK2 OP...

...econd call overwrites the value saved by the first call. Indeed, the second call does not need to save the interrupt state, so it is changed to a simple spin_lock. The semantic match that finds this problem is as follows: (http://www.emn.fr/x-info/coccinelle/) // <smpl> @@ expression lock1,lock2; expression flags; @@ *spin_lock_irqsave(lock1,flags) ... when != flags *spin_lock_irqsave(lock2,flags) // </smpl> Signed-off-by: Julia Lawall <julia@diku.dk> --- fs/btrfs/async-thread.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/btrfs...

On Thu, Mar 19, 2015 at 11:12:42AM +0100, Peter Zijlstra wrote: > So I was now thinking of hashing the lock pointer; let me go and quickly > put something together. A little something like so; ideally we'd allocate the hashtable since NR_CPUS is kinda bloated, but it shows the idea I think. And while this has loops in (the rehashing thing) their fwd progress does not depend on other

On Thu, Mar 19, 2015 at 11:12:42AM +0100, Peter Zijlstra wrote: > So I was now thinking of hashing the lock pointer; let me go and quickly > put something together. A little something like so; ideally we'd allocate the hashtable since NR_CPUS is kinda bloated, but it shows the idea I think. And while this has loops in (the rehashing thing) their fwd progress does not depend on other