Messages in this thread | | | Date | Fri, 13 Jan 2006 13:44:11 -0800 | From | Hans Reiser <> | Subject | Re: [PATCH] reiserfs: use __GFP_NOFAIL instead of yield and retry loop for allocation |
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Do you guys think you could write some nice long comments on these flags regarding what they mean and the policies for using them?
I gotta tell you, lots of people end up just guessing as best as they can.
Hans
Andrew Morton wrote:
>Pekka J Enberg <penberg@cs.Helsinki.FI> wrote: > > >>Hi, >> >>Pekka J Enberg <penberg@cs.Helsinki.FI> wrote: >> >> >>>> - retry: >>>> - jl = kzalloc(sizeof(struct reiserfs_journal_list), GFP_NOFS); >>>> - if (!jl) { >>>> - yield(); >>>> - goto retry; >>>> - } >>>> + jl = kzalloc(sizeof(struct reiserfs_journal_list), >>>> + GFP_NOFS | __GFP_NOFAIL); >>>> >>>> >>On Thu, 12 Jan 2006, Andrew Morton wrote: >> >> >>>yup, that's what __GFP_NOFAIL is for: to consolidate and identify all those >>>places which want to lock up when we're short of memory... They all need >>>fixing, really. >>> >>> >>Out of curiosity, are there any potential problems with combining GFP_NOFS >>and __GFP_NOFAIL? Can we really guarantee to give out memory if we're not >>allowed to page out? >> >> >> > >GFP_NOFS increases the risk (relative to GFP_KERNEL) because page reclaim >can do less things than GFP_KERNEL to free memory. > >GFP_NOFS allocations can still perform swapspace writes, however. GFP_NOIO >cannot even do that. > > > >
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