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Re: extend dl-minimal malloc implementation

• From: Carlos O'Donell <carlos at redhat dot com>
• To: "H.J. Lu" <hjl dot tools at gmail dot com>
• Cc: Zack Weinberg <zackw at panix dot com>, Andreas Schwab <schwab at suse dot de>, DJ Delorie <dj at redhat dot com>, GNU C Library <libc-alpha at sourceware dot org>
• Date: Thu, 17 Aug 2017 09:55:05 -0400
• Subject: Re: extend dl-minimal malloc implementation
• Authentication-results: sourceware.org; auth=none
• References: <8a08bf67-7599-b8df-ce33-2a7cc4cee1c5@redhat.com> <xnmv6zbeel.fsf@greed.delorie.com> <CAKCAbMhUyioOUbXDhQtJ4LPdeT3_PVeBv7X8txwMDQLoSwGBSQ@mail.gmail.com> <mvmlgmir90t.fsf@suse.de> <CAKCAbMjGCMbe9Wg7ivP0OFczZy9irXpgJ7bWDbf+Cvgr+M6HKw@mail.gmail.com> <CAMe9rOqRa+Fx74StPNyVU8bBEYH8+tqTYBXDMQOunEWp0vw26w@mail.gmail.com> <8ad7fde5-8135-af83-ef1a-b2f12cc94314@redhat.com> <CAMe9rOr_dnb8pztb=0xqcEU9ra7y7BH8Tzd=-6jwwbv_8bMRSg@mail.gmail.com>

On 08/17/2017 09:47 AM, H.J. Lu wrote:> On Thu, Aug 17, 2017 at 6:43 AM, Carlos O'Donell <carlos@redhat.com> wrote:>> On 08/17/2017 09:34 AM, H.J. Lu wrote:>>> On Thu, Aug 17, 2017 at 6:10 AM, Zack Weinberg <zackw@panix.com> wrote:>>>> On Thu, Aug 17, 2017 at 2:41 AM, Andreas Schwab <schwab@suse.de> wrote:>>>>> On Aug 16 2017, Zack Weinberg <zackw@panix.com> wrote:>>>>>>>>>>> What I was trying to suggest, earlier, was that *before* either (a) or>>>>>> (b) we should go through the entire of ld.so and try to *remove* as>>>>>> many allocations as possible, at which point it might make sense not>>>>>> to have malloc in there at all - "just" send all remaining allocations>>>>>> directly to mmap (not sbrk; leave sbrk for the "real" malloc).  That>>>>>> may take rearchitecting - but so may just converting alloca to malloc,>>>>>> as you point out. I admit I have no idea whether this is even>>>>>> feasible.>>>>>>>>>> You still need something on top of mmap, unless you want to waste a lot>>>>> of memory.>>>>>>>> _Do_ we, though?  Why does ld.so need to make any allocations at all>>>> above and beyond mapping in the libraries?  It's an open question as>>>> far as I'm concerned.>>>>>> Do we know how many calls to free within ld.so before the regular free>>> takes over?>>>> Yes, DJ had data on this because he tracked it with the new dl-minimal.c>> changes he was working on...>>>> DJ?> > Should we open a bug report for memory leak in ld.so because of> this? No. It's by design.This discussion is about changing the design to have a mostly realmalloc to use during bootstrap.Zack's point is to remove as much malloc as you can and see if westill need such a bootstrap malloc, eventually perhaps forbiddingmalloc in the early bootstrap.-- Cheers,Carlos.

• References:
  • Re: extend dl-minimal malloc implementation
    • From: Carlos O'Donell
  • Re: extend dl-minimal malloc implementation
    • From: DJ Delorie
  • Re: extend dl-minimal malloc implementation
    • From: Zack Weinberg
  • Re: extend dl-minimal malloc implementation
    • From: Andreas Schwab
  • Re: extend dl-minimal malloc implementation
    • From: Zack Weinberg
  • Re: extend dl-minimal malloc implementation
    • From: H.J. Lu
  • Re: extend dl-minimal malloc implementation
    • From: Carlos O'Donell
  • Re: extend dl-minimal malloc implementation
    • From: H.J. Lu